diff --git a/README.md b/README.md
index c9e6dd2..51170db 100644
--- a/README.md
+++ b/README.md
@@ -229,6 +229,72 @@ var upload = multer({
 ```
 You may also use a function as the `contentEncoding`, which should be of the form `function(req, file, cb)`.
 
+## Transforming Files Before Upload
+
+The optional `shouldTransform` option tells multer whether it should transform the file before it is uploaded. By default, it is set to `false`. If set to `true`, `transformers` option must be added, which tells how to transform the file. `transformers` option should be an `Array`, containing objects with can have properties `id`, `key` and `transform`.
+
+```javascript
+var upload = multer({
+  storage: multerS3({
+    s3: s3,
+    bucket: 'some-bucket',
+    shouldTransform: function (req, file, cb) {
+      cb(null, /^image/i.test(file.mimetype))
+    },
+    transformers: [{
+      id: 'original',
+      key: function (req, file, cb) {
+        cb(null, 'image-original.jpg')
+      },
+      transform: function (req, file, cb) {
+        cb(null, sharp().jpeg())
+      }
+    }, {
+      id: 'thumbnail',
+      key: function (req, file, cb) {
+        cb(null, 'image-thumbnail.jpg')
+      },
+      transform: function (req, file, cb) {
+        cb(null, sharp().resize(100, 100).jpeg())
+      }
+    }]
+  })
+})
+```
+If this option is used, each file passed to your router request will have a `transformations` object, with every transform you defined.
+```json
+{
+  "fieldname":"image",
+  "originalname":"image.jpg",
+  "encoding":"7bit",
+  "mimetype":"image/jpg",
+  "transformations":{
+    "original":{
+      "id":"original",
+      "size":18006,
+      "bucket":"some-bucket",
+      "key":"image-original.jpg",
+      "acl":"public-read",
+      "contentType":"image/jpg",
+      "metadata":null,
+      "location":"https://some-bucket.s3.us-east-1.amazonaws.com/image-original.jpg",
+      "etag":"76c09df7bdd752a749f91b9663838fb2"
+    },
+    "thumbnail":{
+      "id":"thumbnail",
+      "size":18006,
+      "bucket":"some-bucket",
+      "key":"image-thumbnail.jpg",
+      "acl":"public-read",
+      "contentType":"image/jpg",
+      "metadata":null,
+      "location":"https://some-bucket.s3.us-east-1.amazonaws.com/image-thumbnail.jpg",
+      "etag":"9d554e03e37c79bff7ce31d375900db6"
+    }
+  }
+}
+```
+
 ## Testing
 
 The tests mock all access to S3 and can be run completely offline.
diff --git a/index.js b/index.js
index f64fa00..052489c 100644
--- a/index.js
+++ b/index.js
@@ -1,21 +1,12 @@
 var crypto = require('crypto')
 var stream = require('stream')
 var fileType = require('file-type')
-var htmlCommentRegex = require('html-comment-regex')
-var parallel = require('run-parallel')
 var Upload = require('@aws-sdk/lib-storage').Upload
 var DeleteObjectCommand = require('@aws-sdk/client-s3').DeleteObjectCommand
 var util = require('util')
 
-function staticValue (value) {
-  return function (req, file, cb) {
-    cb(null, value)
-  }
-}
-
 var defaultAcl = staticValue('private')
 var defaultContentType = staticValue('application/octet-stream')
-
 var defaultMetadata = staticValue(undefined)
 var defaultCacheControl = staticValue(null)
 var defaultContentDisposition = staticValue(null)
@@ -23,21 +14,8 @@ var defaultContentEncoding = staticValue(null)
 var defaultStorageClass = staticValue('STANDARD')
 var defaultSSE = staticValue(null)
 var defaultSSEKMS = staticValue(null)
-
-// Regular expression to detect svg file content, inspired by: https://github.com/sindresorhus/is-svg/blob/master/index.js
-// It is not always possible to check for an end tag if a file is very big. The firstChunk, see below, might not be the entire file.
-var svgRegex = /^\s*(?:<\?xml[^>]*>\s*)?(?:<!doctype svg[^>]*>\s*)?<svg[^>]*>/i
-
-function isSvg (svg) {
-  // Remove DTD entities
-  svg = svg.replace(/\s*<!Entity\s+\S*\s*(?:"|')[^"]+(?:"|')\s*>/img, '')
-  // Remove DTD markup declarations
-  svg = svg.replace(/\[?(?:\s*<![A-Z]+[^>]*>\s*)*\]?/g, '')
-  // Remove HTML comments
-  svg = svg.replace(htmlCommentRegex, '')
-
-  return svgRegex.test(svg)
-}
+var defaultShouldTransform = staticValue(false)
+var defaultTransformers = []
 
 function defaultKey (req, file, cb) {
   crypto.randomBytes(16, function (err, raw) {
@@ -45,29 +23,66 @@ function defaultKey (req, file, cb) {
   })
 }
 
+function staticValue (value) {
+  return function (req, file, cb) {
+    cb(null, value)
+  }
+}
+
+function waterfall (funcs, callback) {
+  var index = 0
+  var values = []
+
+  function next (err, value) {
+    if (err) return callback(err)
+    values.push(value)
+    if (index >= funcs.length) return callback(null, values)
+    funcs[index++](next)
+  }
+
+  funcs[index++](next)
+}
+
 function autoContentType (req, file, cb) {
-  file.stream.once('data', function (firstChunk) {
-    var type = fileType(firstChunk)
-    var mime = 'application/octet-stream' // default type
-
-    // Make sure to check xml-extension for svg files.
-    if ((!type || type.ext === 'xml') && isSvg(firstChunk.toString())) {
-      mime = 'image/svg+xml'
-    } else if (type) {
-      mime = type.mime
-    }
+  // Regular expression to detect svg file content, inspired by: https://github.com/sindresorhus/is-svg/blob/master/index.js
+  // It is not always possible to check for an end tag if a file is very big. The firstChunk, see below, might not be the entire file.
+  var svgRegex = /^\s*(?:<\?xml[^>]*>\s*)?(?:<!doctype svg[^>]*>\s*)?<svg[^>]*>/i
+
+  function isSvg (svg) {
+    // Remove DTD entities
+    svg = svg.replace(/\s*<!Entity\s+\S*\s*(?:"|')[^"]+(?:"|')\s*>/img, '')
+    // Remove DTD markup declarations
+    svg = svg.replace(/\[?(?:\s*<![A-Z]+[^>]*>\s*)*\]?/g, '')
+    // Remove HTML comments
+    svg = svg.replace(/<!--([\s\S]*?)-->/g, '')
+
+    return svgRegex.test(svg)
+  }
+
+  var outStream = new stream.PassThrough()
+
+  stream.pipeline(file.stream, outStream, function (err) {
+    if (err) return cb(err)
+  })
 
-    var outStream = new stream.PassThrough()
+  file.stream.once('data', function (firstChunk) {
+    fileType.fromBuffer(firstChunk).then(function (type) {
+      var mime = 'application/octet-stream' // default type
 
-    outStream.write(firstChunk)
-    file.stream.pipe(outStream)
+      // Make sure to check xml-extension for svg files.
+      if ((!type || type.ext === 'xml') && isSvg(firstChunk.toString())) {
+        mime = 'image/svg+xml'
+      } else if (type) {
+        mime = type.mime
+      }
 
-    cb(null, mime, outStream)
+      cb(null, mime, outStream)
+    })
   })
 }
 
 function collect (storage, req, file, cb) {
-  parallel([
+  waterfall([
     storage.getBucket.bind(storage, req, file),
     storage.getKey.bind(storage, req, file),
     storage.getAcl.bind(storage, req, file),
@@ -77,7 +92,8 @@ function collect (storage, req, file, cb) {
     storage.getStorageClass.bind(storage, req, file),
     storage.getSSE.bind(storage, req, file),
     storage.getSSEKMS.bind(storage, req, file),
-    storage.getContentEncoding.bind(storage, req, file)
+    storage.getContentEncoding.bind(storage, req, file),
+    storage.getShouldTransform.bind(storage, req, file)
   ], function (err, values) {
     if (err) return cb(err)
 
@@ -96,7 +112,8 @@ function collect (storage, req, file, cb) {
         replacementStream: replacementStream,
         serverSideEncryption: values[7],
         sseKmsKeyId: values[8],
-        contentEncoding: values[9]
+        contentEncoding: values[9],
+        shouldTransform: values[10]
       })
     })
   })
@@ -117,6 +134,7 @@ function S3Storage (opts) {
 
   switch (typeof opts.key) {
     case 'function': this.getKey = opts.key; break
+    case 'string': this.getKey = staticValue(opts.key); break
     case 'undefined': this.getKey = defaultKey; break
     default: throw new TypeError('Expected opts.key to be undefined or function')
   }
@@ -130,8 +148,9 @@ function S3Storage (opts) {
 
   switch (typeof opts.contentType) {
     case 'function': this.getContentType = opts.contentType; break
+    case 'string': this.getContentType = staticValue(opts.contentType); break
     case 'undefined': this.getContentType = defaultContentType; break
-    default: throw new TypeError('Expected opts.contentType to be undefined or function')
+    default: throw new TypeError('Expected opts.contentType to be undefined, string or function')
   }
 
   switch (typeof opts.metadata) {
@@ -181,63 +200,154 @@ function S3Storage (opts) {
     case 'undefined': this.getSSEKMS = defaultSSEKMS; break
     default: throw new TypeError('Expected opts.sseKmsKeyId to be undefined, string, or function')
   }
-}
 
-S3Storage.prototype._handleFile = function (req, file, cb) {
-  collect(this, req, file, function (err, opts) {
-    if (err) return cb(err)
+  switch (typeof opts.shouldTransform) {
+    case 'function': this.getShouldTransform = opts.shouldTransform; break
+    case 'boolean': this.getShouldTransform = staticValue(opts.shouldTransform); break
+    case 'undefined': this.getShouldTransform = defaultShouldTransform; break
+    default: throw new TypeError('Expected opts.shouldTransform to be undefined, boolean or function')
+  }
+
+  switch (typeof opts.transformers) {
+    case 'object': this.transformers = opts.transformers; break
+    case 'undefined': this.transformers = defaultTransformers; break
+    default: throw new TypeError('Expected opts.transforms to be undefined or object')
+  }
 
-    var currentSize = 0
-
-    var params = {
-      Bucket: opts.bucket,
-      Key: opts.key,
-      ACL: opts.acl,
-      CacheControl: opts.cacheControl,
-      ContentType: opts.contentType,
-      Metadata: opts.metadata,
-      StorageClass: opts.storageClass,
-      ServerSideEncryption: opts.serverSideEncryption,
-      SSEKMSKeyId: opts.sseKmsKeyId,
-      Body: (opts.replacementStream || file.stream)
+  this.transformers.map(function (transformer) {
+    switch (typeof transformer.id) {
+      case 'string': break
+      default: throw new TypeError('Expected opts.transformer[].id to be string')
     }
 
-    if (opts.contentDisposition) {
-      params.ContentDisposition = opts.contentDisposition
+    switch (typeof transformer.key) {
+      case 'function': break
+      case 'string': transformer.key = staticValue(transformer.key); break
+      case 'undefined': transformer.key = defaultKey(); break
+      default: throw new TypeError('Expected opts.transformer[].key to be unedefined, string or function')
     }
 
-    if (opts.contentEncoding) {
-      params.ContentEncoding = opts.contentEncoding
+    switch (typeof transformer.transform) {
+      case 'function': break
+      default: throw new TypeError('Expected opts.transformer[].transform to be function')
     }
 
-    var upload = new Upload({
-      client: this.s3,
-      params: params
-    })
+    switch (typeof transformer.contentType) {
+      case 'function': transformer.getContentType = transformer.contentType; break
+      case 'string': transformer.getContentType = staticValue(transformer.contentType); break
+      case 'undefined': transformer.getContentType = staticValue(undefined); break
+      default: throw new TypeError('Expected opts.transformer[].contentType to be undefined, string or function')
+    }
+
+    return transformer
+  })
+}
+
+S3Storage.prototype.directUpload = function (opts, file, cb) {
+  var currentSize = 0
+
+  var params = {
+    Bucket: opts.bucket,
+    Key: opts.key,
+    ACL: opts.acl,
+    CacheControl: opts.cacheControl,
+    ContentType: opts.contentType,
+    Metadata: opts.metadata,
+    StorageClass: opts.storageClass,
+    ServerSideEncryption: opts.serverSideEncryption,
+    SSEKMSKeyId: opts.sseKmsKeyId,
+    Body: opts.piper ? (opts.replacementStream || file.stream).pipe(opts.piper) : (opts.replacementStream || file.stream)
+  }
+
+  if (opts.contentDisposition) {
+    params.ContentDisposition = opts.contentDisposition
+  }
 
-    upload.on('httpUploadProgress', function (ev) {
-      if (ev.total) currentSize = ev.total
+  if (opts.contentEncoding) {
+    params.ContentEncoding = opts.contentEncoding
+  }
+
+  var upload = new Upload({
+    client: this.s3,
+    params: params
+  })
+
+  upload.on('httpUploadProgress', function (ev) {
+    if (ev.total) currentSize = ev.total
+  })
+
+  util.callbackify(upload.done.bind(upload))(function (err, result) {
+    if (err) return cb(err)
+
+    cb(null, {
+      id: opts.id,
+      size: currentSize,
+      bucket: opts.bucket,
+      key: opts.key,
+      acl: opts.acl,
+      contentType: opts.contentType,
+      contentDisposition: opts.contentDisposition,
+      contentEncoding: opts.contentEncoding,
+      storageClass: opts.storageClass,
+      serverSideEncryption: opts.serverSideEncryption,
+      metadata: opts.metadata,
+      location: result.Location,
+      etag: result.ETag,
+      versionId: result.VersionId
     })
+  })
+}
+
+S3Storage.prototype.transformUpload = function (opts, req, file, cb) {
+  var storage = this
+  var transformations = {}
+  var pending = storage.transformers.length
 
-    util.callbackify(upload.done.bind(upload))(function (err, result) {
+  waterfall(
+    storage.transformers.map(function (transform) {
+      return transform.key.bind(storage, req, file)
+    }),
+    function (err, keys) {
       if (err) return cb(err)
 
-      cb(null, {
-        size: currentSize,
-        bucket: opts.bucket,
-        key: opts.key,
-        acl: opts.acl,
-        contentType: opts.contentType,
-        contentDisposition: opts.contentDisposition,
-        contentEncoding: opts.contentEncoding,
-        storageClass: opts.storageClass,
-        serverSideEncryption: opts.serverSideEncryption,
-        metadata: opts.metadata,
-        location: result.Location,
-        etag: result.ETag,
-        versionId: result.VersionId
+      keys.forEach(function (key, i) {
+        var transform = storage.transformers[i].transform.bind(storage, req, file)
+        var getContentType = storage.transformers[i].getContentType.bind(storage, req, file)
+
+        getContentType(function (err, contentType) {
+          if (err) return cb(err)
+
+          transform(function (err, piper) {
+            if (err) return cb(err)
+
+            var transformerOpts = Object.assign({}, opts)
+            transformerOpts.id = storage.transformers[i].id || i
+            transformerOpts.key = key
+            transformerOpts.contentType = contentType || transformerOpts.contentType
+            transformerOpts.piper = piper
+
+            storage.directUpload(transformerOpts, file, function (err, result) {
+              if (err) return cb(err)
+
+              transformations[transformerOpts.id] = result
+              if (--pending === 0) cb(null, { transformations: transformations })
+            })
+          })
+        })
       })
-    })
+    }
+  )
+}
+
+S3Storage.prototype._handleFile = function (req, file, cb) {
+  collect(this, req, file, function (err, opts) {
+    if (err) return cb(err)
+
+    if (opts.shouldTransform) {
+      this.transformUpload(opts, req, file, cb)
+    } else {
+      this.directUpload(opts, file, cb)
+    }
   })
 }
 
diff --git a/package-lock.json b/package-lock.json
index 6d8f601..e30e90a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -10,9 +10,7 @@
       "license": "MIT",
       "dependencies": {
         "@aws-sdk/lib-storage": "^3.46.0",
-        "file-type": "^3.3.0",
-        "html-comment-regex": "^1.1.2",
-        "run-parallel": "^1.1.6"
+        "file-type": "^16.5.4"
       },
       "devDependencies": {
         "express": "^4.13.1",
@@ -1326,6 +1324,11 @@
         "node": ">= 12.0.0"
       }
     },
+    "node_modules/@tokenizer/token": {
+      "version": "0.3.0",
+      "resolved": "https://registry.npmjs.org/@tokenizer/token/-/token-0.3.0.tgz",
+      "integrity": "sha512-OvjF+z51L3ov0OyAU0duzsYuvO01PH7x4t6DJx+guahgTnBHkhJdG7soQeTSFLWN3efnHyibZ4Z8l2EuWwJN3A=="
+    },
     "node_modules/abbrev": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/abbrev/-/abbrev-1.1.1.tgz",
@@ -3255,11 +3258,19 @@
       }
     },
     "node_modules/file-type": {
-      "version": "3.9.0",
-      "resolved": "https://registry.npmjs.org/file-type/-/file-type-3.9.0.tgz",
-      "integrity": "sha512-RLoqTXE8/vPmMuTI88DAzhMYC99I8BWv7zYP4A1puo5HIjEJ5EX48ighy4ZyKMG9EDXxBgW6e++cn7d1xuFghA==",
+      "version": "16.5.4",
+      "resolved": "https://registry.npmjs.org/file-type/-/file-type-16.5.4.tgz",
+      "integrity": "sha512-/yFHK0aGjFEgDJjEKP0pWCplsPFPhwyfwevf/pVxiN0tmE4L9LmwWxWukdJSHdoCli4VgQLehjJtwQBnqmsKcw==",
+      "dependencies": {
+        "readable-web-to-node-stream": "^3.0.0",
+        "strtok3": "^6.2.4",
+        "token-types": "^4.1.1"
+      },
       "engines": {
-        "node": ">=0.10.0"
+        "node": ">=10"
+      },
+      "funding": {
+        "url": "https://github.com/sindresorhus/file-type?sponsor=1"
       }
     },
     "node_modules/finalhandler": {
@@ -3535,11 +3546,6 @@
         "node": ">=0.10.0"
       }
     },
-    "node_modules/html-comment-regex": {
-      "version": "1.1.2",
-      "resolved": "https://registry.npmjs.org/html-comment-regex/-/html-comment-regex-1.1.2.tgz",
-      "integrity": "sha512-P+M65QY2JQ5Y0G9KKdlDpo0zK+/OHptU5AaBwUfAIDJZk1MYf32Frm84EcOytfJE0t5JvkAnKlmjsXDnWzCJmQ=="
-    },
     "node_modules/http-errors": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/http-errors/-/http-errors-2.0.0.tgz",
@@ -4730,6 +4736,18 @@
       "integrity": "sha1-32BBeABfUi8V60SQ5yR6G/qmf4w=",
       "dev": true
     },
+    "node_modules/peek-readable": {
+      "version": "4.1.0",
+      "resolved": "https://registry.npmjs.org/peek-readable/-/peek-readable-4.1.0.tgz",
+      "integrity": "sha512-ZI3LnwUv5nOGbQzD9c2iDG6toheuXSZP5esSHBjopsXH4dg19soufvpUGA3uohi5anFtGb2lhAVdHzH6R/Evvg==",
+      "engines": {
+        "node": ">=8"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Borewit"
+      }
+    },
     "node_modules/pkg-config": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/pkg-config/-/pkg-config-1.1.1.tgz",
@@ -4834,6 +4852,7 @@
       "version": "1.2.3",
       "resolved": "https://registry.npmjs.org/queue-microtask/-/queue-microtask-1.2.3.tgz",
       "integrity": "sha512-NuaNSa6flKT5JaSYQzJok04JzTL1CA6aGhv5rfLW3PgqA+M2ChpZQnAC8h8i4ZFkBS8X5RqkDBHA7r4hej3K9A==",
+      "dev": true,
       "funding": [
         {
           "type": "github",
@@ -4885,6 +4904,42 @@
         "string_decoder": "~0.10.x"
       }
     },
+    "node_modules/readable-web-to-node-stream": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/readable-web-to-node-stream/-/readable-web-to-node-stream-3.0.2.tgz",
+      "integrity": "sha512-ePeK6cc1EcKLEhJFt/AebMCLL+GgSKhuygrZ/GLaKZYEecIgIECf4UaUuaByiGtzckwR4ain9VzUh95T1exYGw==",
+      "dependencies": {
+        "readable-stream": "^3.6.0"
+      },
+      "engines": {
+        "node": ">=8"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Borewit"
+      }
+    },
+    "node_modules/readable-web-to-node-stream/node_modules/readable-stream": {
+      "version": "3.6.1",
+      "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-3.6.1.tgz",
+      "integrity": "sha512-+rQmrWMYGA90yenhTYsLWAsLsqVC8osOw6PKE1HDYiO0gdPeKe/xDHNzIAIn4C91YQ6oenEhfYqqc1883qHbjQ==",
+      "dependencies": {
+        "inherits": "^2.0.3",
+        "string_decoder": "^1.1.1",
+        "util-deprecate": "^1.0.1"
+      },
+      "engines": {
+        "node": ">= 6"
+      }
+    },
+    "node_modules/readable-web-to-node-stream/node_modules/string_decoder": {
+      "version": "1.3.0",
+      "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.3.0.tgz",
+      "integrity": "sha512-hkRX8U1WjJFd8LsDJ2yQ/wWWxaopEsABU1XfkM8A+j0+85JAGppt16cr1Whg6KIbb4okU6Mql6BOj+uup/wKeA==",
+      "dependencies": {
+        "safe-buffer": "~5.2.0"
+      }
+    },
     "node_modules/readline2": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/readline2/-/readline2-1.0.1.tgz",
@@ -5204,6 +5259,7 @@
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/run-parallel/-/run-parallel-1.2.0.tgz",
       "integrity": "sha512-5l4VyZR86LZ/lDxZTR6jqL8AFE2S0IFLMP26AbjsLVADxHdhB/c0GUsH+y39UfCi3dzz8OlQuPmnaJOMoDHQBA==",
+      "dev": true,
       "funding": [
         {
           "type": "github",
@@ -5637,6 +5693,22 @@
         "node": ">=0.8.0"
       }
     },
+    "node_modules/strtok3": {
+      "version": "6.3.0",
+      "resolved": "https://registry.npmjs.org/strtok3/-/strtok3-6.3.0.tgz",
+      "integrity": "sha512-fZtbhtvI9I48xDSywd/somNqgUHl2L2cstmXCCif0itOf96jeW18MBSyrLuNicYQVkvpOxkZtkzujiTJ9LW5Jw==",
+      "dependencies": {
+        "@tokenizer/token": "^0.3.0",
+        "peek-readable": "^4.1.0"
+      },
+      "engines": {
+        "node": ">=10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Borewit"
+      }
+    },
     "node_modules/supports-color": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-1.2.0.tgz",
@@ -5722,6 +5794,22 @@
         "node": ">=0.6"
       }
     },
+    "node_modules/token-types": {
+      "version": "4.2.1",
+      "resolved": "https://registry.npmjs.org/token-types/-/token-types-4.2.1.tgz",
+      "integrity": "sha512-6udB24Q737UD/SDsKAHI9FCRP7Bqc9D/MQUV02ORQg5iskjtLJlZJNdN4kKtcdtwCeWIwIHDGaUsTsCCAa8sFQ==",
+      "dependencies": {
+        "@tokenizer/token": "^0.3.0",
+        "ieee754": "^1.2.1"
+      },
+      "engines": {
+        "node": ">=10"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/Borewit"
+      }
+    },
     "node_modules/trim-right": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/trim-right/-/trim-right-1.0.1.tgz",
@@ -7056,6 +7144,11 @@
         "tslib": "^2.3.1"
       }
     },
+    "@tokenizer/token": {
+      "version": "0.3.0",
+      "resolved": "https://registry.npmjs.org/@tokenizer/token/-/token-0.3.0.tgz",
+      "integrity": "sha512-OvjF+z51L3ov0OyAU0duzsYuvO01PH7x4t6DJx+guahgTnBHkhJdG7soQeTSFLWN3efnHyibZ4Z8l2EuWwJN3A=="
+    },
     "abbrev": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/abbrev/-/abbrev-1.1.1.tgz",
@@ -8691,9 +8784,14 @@
       }
     },
     "file-type": {
-      "version": "3.9.0",
-      "resolved": "https://registry.npmjs.org/file-type/-/file-type-3.9.0.tgz",
-      "integrity": "sha512-RLoqTXE8/vPmMuTI88DAzhMYC99I8BWv7zYP4A1puo5HIjEJ5EX48ighy4ZyKMG9EDXxBgW6e++cn7d1xuFghA=="
+      "version": "16.5.4",
+      "resolved": "https://registry.npmjs.org/file-type/-/file-type-16.5.4.tgz",
+      "integrity": "sha512-/yFHK0aGjFEgDJjEKP0pWCplsPFPhwyfwevf/pVxiN0tmE4L9LmwWxWukdJSHdoCli4VgQLehjJtwQBnqmsKcw==",
+      "requires": {
+        "readable-web-to-node-stream": "^3.0.0",
+        "strtok3": "^6.2.4",
+        "token-types": "^4.1.1"
+      }
     },
     "finalhandler": {
       "version": "1.2.0",
@@ -8913,11 +9011,6 @@
         }
       }
     },
-    "html-comment-regex": {
-      "version": "1.1.2",
-      "resolved": "https://registry.npmjs.org/html-comment-regex/-/html-comment-regex-1.1.2.tgz",
-      "integrity": "sha512-P+M65QY2JQ5Y0G9KKdlDpo0zK+/OHptU5AaBwUfAIDJZk1MYf32Frm84EcOytfJE0t5JvkAnKlmjsXDnWzCJmQ=="
-    },
     "http-errors": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/http-errors/-/http-errors-2.0.0.tgz",
@@ -9913,6 +10006,11 @@
       "integrity": "sha1-32BBeABfUi8V60SQ5yR6G/qmf4w=",
       "dev": true
     },
+    "peek-readable": {
+      "version": "4.1.0",
+      "resolved": "https://registry.npmjs.org/peek-readable/-/peek-readable-4.1.0.tgz",
+      "integrity": "sha512-ZI3LnwUv5nOGbQzD9c2iDG6toheuXSZP5esSHBjopsXH4dg19soufvpUGA3uohi5anFtGb2lhAVdHzH6R/Evvg=="
+    },
     "pkg-config": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/pkg-config/-/pkg-config-1.1.1.tgz",
@@ -9996,7 +10094,8 @@
     "queue-microtask": {
       "version": "1.2.3",
       "resolved": "https://registry.npmjs.org/queue-microtask/-/queue-microtask-1.2.3.tgz",
-      "integrity": "sha512-NuaNSa6flKT5JaSYQzJok04JzTL1CA6aGhv5rfLW3PgqA+M2ChpZQnAC8h8i4ZFkBS8X5RqkDBHA7r4hej3K9A=="
+      "integrity": "sha512-NuaNSa6flKT5JaSYQzJok04JzTL1CA6aGhv5rfLW3PgqA+M2ChpZQnAC8h8i4ZFkBS8X5RqkDBHA7r4hej3K9A==",
+      "dev": true
     },
     "range-parser": {
       "version": "1.2.1",
@@ -10028,6 +10127,34 @@
         "string_decoder": "~0.10.x"
       }
     },
+    "readable-web-to-node-stream": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/readable-web-to-node-stream/-/readable-web-to-node-stream-3.0.2.tgz",
+      "integrity": "sha512-ePeK6cc1EcKLEhJFt/AebMCLL+GgSKhuygrZ/GLaKZYEecIgIECf4UaUuaByiGtzckwR4ain9VzUh95T1exYGw==",
+      "requires": {
+        "readable-stream": "^3.6.0"
+      },
+      "dependencies": {
+        "readable-stream": {
+          "version": "3.6.1",
+          "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-3.6.1.tgz",
+          "integrity": "sha512-+rQmrWMYGA90yenhTYsLWAsLsqVC8osOw6PKE1HDYiO0gdPeKe/xDHNzIAIn4C91YQ6oenEhfYqqc1883qHbjQ==",
+          "requires": {
+            "inherits": "^2.0.3",
+            "string_decoder": "^1.1.1",
+            "util-deprecate": "^1.0.1"
+          }
+        },
+        "string_decoder": {
+          "version": "1.3.0",
+          "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.3.0.tgz",
+          "integrity": "sha512-hkRX8U1WjJFd8LsDJ2yQ/wWWxaopEsABU1XfkM8A+j0+85JAGppt16cr1Whg6KIbb4okU6Mql6BOj+uup/wKeA==",
+          "requires": {
+            "safe-buffer": "~5.2.0"
+          }
+        }
+      }
+    },
     "readline2": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/readline2/-/readline2-1.0.1.tgz",
@@ -10291,6 +10418,7 @@
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/run-parallel/-/run-parallel-1.2.0.tgz",
       "integrity": "sha512-5l4VyZR86LZ/lDxZTR6jqL8AFE2S0IFLMP26AbjsLVADxHdhB/c0GUsH+y39UfCi3dzz8OlQuPmnaJOMoDHQBA==",
+      "dev": true,
       "requires": {
         "queue-microtask": "^1.2.2"
       }
@@ -10641,6 +10769,15 @@
       "integrity": "sha1-HhX7ysl9Pumb8tc7TGVrCCu6+5E=",
       "dev": true
     },
+    "strtok3": {
+      "version": "6.3.0",
+      "resolved": "https://registry.npmjs.org/strtok3/-/strtok3-6.3.0.tgz",
+      "integrity": "sha512-fZtbhtvI9I48xDSywd/somNqgUHl2L2cstmXCCif0itOf96jeW18MBSyrLuNicYQVkvpOxkZtkzujiTJ9LW5Jw==",
+      "requires": {
+        "@tokenizer/token": "^0.3.0",
+        "peek-readable": "^4.1.0"
+      }
+    },
     "supports-color": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-1.2.0.tgz",
@@ -10701,6 +10838,15 @@
       "integrity": "sha512-o5sSPKEkg/DIQNmH43V0/uerLrpzVedkUh8tGNvaeXpfpuwjKenlSox/2O/BTlZUtEe+JG7s5YhEz608PlAHRA==",
       "dev": true
     },
+    "token-types": {
+      "version": "4.2.1",
+      "resolved": "https://registry.npmjs.org/token-types/-/token-types-4.2.1.tgz",
+      "integrity": "sha512-6udB24Q737UD/SDsKAHI9FCRP7Bqc9D/MQUV02ORQg5iskjtLJlZJNdN4kKtcdtwCeWIwIHDGaUsTsCCAa8sFQ==",
+      "requires": {
+        "@tokenizer/token": "^0.3.0",
+        "ieee754": "^1.2.1"
+      }
+    },
     "trim-right": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/trim-right/-/trim-right-1.0.1.tgz",
diff --git a/package.json b/package.json
index e1a31a1..7cfcceb 100644
--- a/package.json
+++ b/package.json
@@ -27,9 +27,7 @@
   "homepage": "https://github.com/badunk/multer-s3#readme",
   "dependencies": {
     "@aws-sdk/lib-storage": "^3.46.0",
-    "file-type": "^3.3.0",
-    "html-comment-regex": "^1.1.2",
-    "run-parallel": "^1.1.6"
+    "file-type": "^16.5.4"
   },
   "peerDependencies": {
     "@aws-sdk/client-s3": "^3.0.0"
diff --git a/test/basic.js b/test/basic.js
index 9b7dc2f..a6f3ae6 100644
--- a/test/basic.js
+++ b/test/basic.js
@@ -64,7 +64,7 @@ describe('Multer S3', function () {
   it('upload files', function (done) {
     var s3 = mockS3()
     var form = new FormData()
-    var storage = multerS3({ s3: s3, bucket: 'test' })
+    var storage = multerS3({ s3: s3, bucket: 'test', key: 'mock-location' })
     var upload = multer({ storage: storage })
     var parser = upload.single('image')
     var image = fs.createReadStream(path.join(__dirname, 'files', 'ffffff.png'))
@@ -82,7 +82,7 @@ describe('Multer S3', function () {
       assert.equal(req.file.size, 68)
       assert.equal(req.file.bucket, 'test')
       assert.equal(req.file.etag, 'mock-etag')
-      assert.equal(req.file.location, 'mock-location')
+      assert.equal(req.file.location, 'https//test.hostname/mock-location')
 
       done()
     })
@@ -91,7 +91,7 @@ describe('Multer S3', function () {
   it('uploads file with AES256 server-side encryption', function (done) {
     var s3 = mockS3()
     var form = new FormData()
-    var storage = multerS3({ s3: s3, bucket: 'test', serverSideEncryption: 'AES256' })
+    var storage = multerS3({ s3: s3, bucket: 'test', key: 'mock-location', serverSideEncryption: 'AES256' })
     var upload = multer({ storage: storage })
     var parser = upload.single('image')
     var image = fs.createReadStream(path.join(__dirname, 'files', 'ffffff.png'))
@@ -109,7 +109,7 @@ describe('Multer S3', function () {
       assert.equal(req.file.size, 68)
       assert.equal(req.file.bucket, 'test')
       assert.equal(req.file.etag, 'mock-etag')
-      assert.equal(req.file.location, 'mock-location')
+      assert.equal(req.file.location, 'https//test.hostname/mock-location')
       assert.equal(req.file.serverSideEncryption, 'AES256')
 
       done()
@@ -119,7 +119,7 @@ describe('Multer S3', function () {
   it('uploads file with AWS KMS-managed server-side encryption', function (done) {
     var s3 = mockS3()
     var form = new FormData()
-    var storage = multerS3({ s3: s3, bucket: 'test', serverSideEncryption: 'aws:kms' })
+    var storage = multerS3({ s3: s3, bucket: 'test', key: 'mock-location', serverSideEncryption: 'aws:kms' })
     var upload = multer({ storage: storage })
     var parser = upload.single('image')
     var image = fs.createReadStream(path.join(__dirname, 'files', 'ffffff.png'))
@@ -137,7 +137,7 @@ describe('Multer S3', function () {
       assert.equal(req.file.size, 68)
       assert.equal(req.file.bucket, 'test')
       assert.equal(req.file.etag, 'mock-etag')
-      assert.equal(req.file.location, 'mock-location')
+      assert.equal(req.file.location, 'https//test.hostname/mock-location')
       assert.equal(req.file.serverSideEncryption, 'aws:kms')
 
       done()
@@ -147,7 +147,7 @@ describe('Multer S3', function () {
   it('uploads PNG file with correct content-type', function (done) {
     var s3 = mockS3()
     var form = new FormData()
-    var storage = multerS3({ s3: s3, bucket: 'test', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE })
+    var storage = multerS3({ s3: s3, bucket: 'test', key: 'mock-location', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE })
     var upload = multer({ storage: storage })
     var parser = upload.single('image')
     var image = fs.createReadStream(path.join(__dirname, 'files', 'ffffff.png'))
@@ -166,7 +166,7 @@ describe('Multer S3', function () {
       assert.equal(req.file.size, 68)
       assert.equal(req.file.bucket, 'test')
       assert.equal(req.file.etag, 'mock-etag')
-      assert.equal(req.file.location, 'mock-location')
+      assert.equal(req.file.location, 'https//test.hostname/mock-location')
       assert.equal(req.file.serverSideEncryption, 'aws:kms')
 
       done()
@@ -176,7 +176,7 @@ describe('Multer S3', function () {
   it('uploads pure SVG file with correct content-type', function (done) {
     var s3 = mockS3()
     var form = new FormData()
-    var storage = multerS3({ s3: s3, bucket: 'test', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE })
+    var storage = multerS3({ s3: s3, bucket: 'test', key: 'mock-location', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE })
     var upload = multer({ storage: storage })
     var parser = upload.single('image')
     var image = fs.createReadStream(path.join(__dirname, 'files', 'test.svg'))
@@ -195,7 +195,7 @@ describe('Multer S3', function () {
       assert.equal(req.file.size, 100)
       assert.equal(req.file.bucket, 'test')
       assert.equal(req.file.etag, 'mock-etag')
-      assert.equal(req.file.location, 'mock-location')
+      assert.equal(req.file.location, 'https//test.hostname/mock-location')
       assert.equal(req.file.serverSideEncryption, 'aws:kms')
 
       done()
@@ -205,7 +205,7 @@ describe('Multer S3', function () {
   it('uploads common SVG file with correct content-type', function (done) {
     var s3 = mockS3()
     var form = new FormData()
-    var storage = multerS3({ s3: s3, bucket: 'test', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE })
+    var storage = multerS3({ s3: s3, bucket: 'test', key: 'mock-location', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE })
     var upload = multer({ storage: storage })
     var parser = upload.single('image')
     var image = fs.createReadStream(path.join(__dirname, 'files', 'test2.svg'))
@@ -224,7 +224,7 @@ describe('Multer S3', function () {
       assert.equal(req.file.size, 285)
       assert.equal(req.file.bucket, 'test')
       assert.equal(req.file.etag, 'mock-etag')
-      assert.equal(req.file.location, 'mock-location')
+      assert.equal(req.file.location, 'https//test.hostname/mock-location')
       assert.equal(req.file.serverSideEncryption, 'aws:kms')
 
       done()
@@ -236,7 +236,7 @@ describe('Multer S3', function () {
 
     var s3 = mockS3()
     var form = new FormData()
-    var storage = multerS3({ s3: s3, bucket: 'test', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE })
+    var storage = multerS3({ s3: s3, bucket: 'test', key: 'mock-location', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE })
     var upload = multer({ storage: storage })
     var parser = upload.single('image')
     fs.writeFileSync(path.join(__dirname, 'files', 'test_generated.svg'), '<!doctype svg ' + ' '.repeat(34560))
@@ -256,7 +256,7 @@ describe('Multer S3', function () {
       assert.equal(req.file.size, 34574)
       assert.equal(req.file.bucket, 'test')
       assert.equal(req.file.etag, 'mock-etag')
-      assert.equal(req.file.location, 'mock-location')
+      assert.equal(req.file.location, 'https//test.hostname/mock-location')
       assert.equal(req.file.serverSideEncryption, 'aws:kms')
 
       done()
@@ -266,7 +266,7 @@ describe('Multer S3', function () {
   it('uploads common file as gzip content encoded', function (done) {
     var s3 = mockS3()
     var form = new FormData()
-    var storage = multerS3({ s3: s3, bucket: 'test', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE, contentEncoding: 'gzip' })
+    var storage = multerS3({ s3: s3, bucket: 'test', key: 'mock-location', serverSideEncryption: 'aws:kms', contentType: multerS3.AUTO_CONTENT_TYPE, contentEncoding: 'gzip' })
     var upload = multer({ storage: storage })
     var parser = upload.single('file')
     var image = fs.createReadStream(path.join(__dirname, 'files', 'a.txt'))
@@ -284,10 +284,172 @@ describe('Multer S3', function () {
       assert.equal(req.file.size, 7)
       assert.equal(req.file.bucket, 'test')
       assert.equal(req.file.etag, 'mock-etag')
-      assert.equal(req.file.location, 'mock-location')
+      assert.equal(req.file.location, 'https//test.hostname/mock-location')
       assert.equal(req.file.serverSideEncryption, 'aws:kms')
       assert.equal(req.file.contentEncoding, 'gzip')
       done()
     })
   })
+
+  it('uploads PNG file with transformers', function (done) {
+    var s3 = mockS3()
+    var form = new FormData()
+    var storage = multerS3({
+      s3: s3,
+      bucket: 'test',
+      contentType: multerS3.AUTO_CONTENT_TYPE,
+      shouldTransform: true,
+      transformers: [
+        {
+          id: 'original',
+          key: 'original',
+          transform: function (req, file, cb) {
+            cb(null, new stream.PassThrough())
+          }
+        },
+        {
+          id: 'thumbnail',
+          key: function (req, file, cb) {
+            cb(null, 'thumbnail')
+          },
+          transform: function (req, file, cb) {
+            cb(null, new stream.PassThrough())
+          },
+          contentType: 'image/webp'
+        }
+      ]
+    })
+    var upload = multer({ storage: storage })
+    var parser = upload.single('image')
+    var image = fs.createReadStream(path.join(__dirname, 'files', 'ffffff.png'))
+
+    form.append('name', 'Multer')
+    form.append('image', image)
+
+    submitForm(parser, form, function (err, req) {
+      assert.ifError(err)
+
+      assert.equal(req.body.name, 'Multer')
+
+      assert.equal(req.file.fieldname, 'image')
+      assert.equal(req.file.mimetype, 'image/png')
+      assert.equal(req.file.originalname, 'ffffff.png')
+      assert.equal(req.file.transformations.original.size, 68)
+      assert.equal(req.file.transformations.original.bucket, 'test')
+      assert.equal(req.file.transformations.original.etag, 'mock-etag')
+      assert.equal(req.file.transformations.original.location, 'https//test.hostname/original')
+      assert.equal(req.file.transformations.original.contentType, 'image/png')
+      assert.equal(req.file.transformations.thumbnail.size, 68)
+      assert.equal(req.file.transformations.thumbnail.bucket, 'test')
+      assert.equal(req.file.transformations.thumbnail.etag, 'mock-etag')
+      assert.equal(req.file.transformations.thumbnail.location, 'https//test.hostname/thumbnail')
+      assert.equal(req.file.transformations.thumbnail.contentType, 'image/webp')
+
+      done()
+    })
+  })
+
+  it('uploads a PNG and SVG file with transforms', function (done) {
+    var s3 = mockS3()
+    var form = new FormData()
+    var storage = multerS3({
+      s3: s3,
+      bucket: 'test',
+      contentType: multerS3.AUTO_CONTENT_TYPE,
+      shouldTransform: true,
+      transformers: [
+        {
+          id: 'original',
+          key: 'original',
+          transform: function (req, file, cb) {
+            cb(null, new stream.PassThrough())
+          }
+        },
+        {
+          id: 'thumbnail',
+          key: function (req, file, cb) {
+            cb(null, 'thumbnail')
+          },
+          transform: function (req, file, cb) {
+            cb(null, new stream.PassThrough())
+          }
+        }
+      ]
+    })
+    var upload = multer({ storage: storage })
+    var parser = upload.array('images', 2)
+    var image1 = fs.createReadStream(path.join(__dirname, 'files', 'ffffff.png'))
+    var image2 = fs.createReadStream(path.join(__dirname, 'files', 'test2.svg'))
+
+    form.append('name', 'Multer')
+    form.append('images', image1)
+    form.append('images', image2)
+
+    submitForm(parser, form, function (err, req) {
+      assert.ifError(err)
+
+      assert.equal(req.body.name, 'Multer')
+
+      assert.equal(req.files[0].fieldname, 'images')
+      assert.equal(req.files[0].mimetype, 'image/png')
+      assert.equal(req.files[0].originalname, 'ffffff.png')
+      assert.equal(req.files[0].transformations.original.size, 68)
+      assert.equal(req.files[0].transformations.original.bucket, 'test')
+      assert.equal(req.files[0].transformations.original.etag, 'mock-etag')
+      assert.equal(req.files[0].transformations.original.location, 'https//test.hostname/original')
+      assert.equal(req.files[0].transformations.thumbnail.size, 68)
+      assert.equal(req.files[0].transformations.thumbnail.bucket, 'test')
+      assert.equal(req.files[0].transformations.thumbnail.etag, 'mock-etag')
+      assert.equal(req.files[0].transformations.thumbnail.location, 'https//test.hostname/thumbnail')
+
+      assert.equal(req.files[1].fieldname, 'images')
+      assert.equal(req.files[1].mimetype, 'image/svg+xml')
+      assert.equal(req.files[1].originalname, 'test2.svg')
+
+      done()
+    })
+  })
+
+  it('uploads a PNG and SVG file', function (done) {
+    var s3 = mockS3()
+    var form = new FormData()
+    var storage = multerS3({
+      s3: s3,
+      bucket: 'test',
+      key: 'mock-location',
+      contentType: multerS3.AUTO_CONTENT_TYPE
+    })
+    var upload = multer({ storage: storage })
+    var parser = upload.array('images', 2)
+    var image1 = fs.createReadStream(path.join(__dirname, 'files', 'ffffff.png'))
+    var image2 = fs.createReadStream(path.join(__dirname, 'files', 'test2.svg'))
+
+    form.append('name', 'Multer')
+    form.append('images', image1)
+    form.append('images', image2)
+
+    submitForm(parser, form, function (err, req) {
+      assert.ifError(err)
+
+      assert.equal(req.body.name, 'Multer')
+
+      assert.equal(req.files[0].fieldname, 'images')
+      assert.equal(req.files[0].mimetype, 'image/png')
+      assert.equal(req.files[0].originalname, 'ffffff.png')
+      assert.equal(req.files[0].size, 68)
+      assert.equal(req.files[0].bucket, 'test')
+      assert.equal(req.files[0].etag, 'mock-etag')
+      assert.equal(req.files[0].location, 'https//test.hostname/mock-location')
+
+      assert.equal(req.files[1].fieldname, 'images')
+      assert.equal(req.files[1].mimetype, 'image/svg+xml')
+      assert.equal(req.files[1].originalname, 'test2.svg')
+      assert.equal(req.files[1].size, 285)
+      assert.equal(req.files[1].bucket, 'test')
+      assert.equal(req.files[1].etag, 'mock-etag')
+      assert.equal(req.files[1].location, 'https//test.hostname/mock-location')
+
+      done()
+    })
+  })
 })
diff --git a/test/util/mock-s3.js b/test/util/mock-s3.js
index 6609b99..2a417f1 100644
--- a/test/util/mock-s3.js
+++ b/test/util/mock-s3.js
@@ -11,7 +11,7 @@ function createMockS3 () {
     })
   }
 
-  return { send: send }
+  return { send: send, config: { endpoint: () => ({ protocol: 'https', hostname: 'hostname' }) } }
 }
 
 module.exports = createMockS3