diff --git a/packages/core/src/commands/command.ts b/packages/core/src/commands/command.ts
new file mode 100644
index 000000000..7f129d422
--- /dev/null
+++ b/packages/core/src/commands/command.ts
@@ -0,0 +1,5 @@
+import { Command } from '../types'
+
+export default (fn: (props: Parameters<Command>[0]) => boolean): Command => props => {
+  return fn(props)
+}
diff --git a/packages/core/src/extensions/commands.ts b/packages/core/src/extensions/commands.ts
index 3b82b620a..ae0feba28 100644
--- a/packages/core/src/extensions/commands.ts
+++ b/packages/core/src/extensions/commands.ts
@@ -1,6 +1,7 @@
 import { Extension } from '../Extension'
 import blur from '../commands/blur'
 import clearContent from '../commands/clearContent'
+import command from '../commands/command'
 import clearNodes from '../commands/clearNodes'
 import deleteSelection from '../commands/deleteSelection'
 import extendMarkRange from '../commands/extendMarkRange'
@@ -43,6 +44,10 @@ export const Commands = Extension.create({
        * Normalize nodes to a simple paragraph.
        */
       clearNodes,
+      /**
+       * Define a command inline.
+       */
+      command,
       /**
        * Delete the selection, if there is one.
        */
diff --git a/yarn.lock b/yarn.lock
index 6f3c307c8..a1af051ac 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2801,6 +2801,28 @@ abbrev@1:
   resolved "https://registry.yarnpkg.com/abbrev/-/abbrev-1.1.1.tgz#f8f2c887ad10bf67f634f005b6987fed3179aac8"
   integrity sha512-nne9/IiQ/hzIhY6pdDnbBtz7DjPTKrY00P/zvPSm5pOFkl6xuGrGnXn/VtTNNfNtAfZ9/1RtehkszU9qcTii0Q==
 
+abstract-leveldown@^6.2.1:
+  version "6.3.0"
+  resolved "https://registry.yarnpkg.com/abstract-leveldown/-/abstract-leveldown-6.3.0.tgz#d25221d1e6612f820c35963ba4bd739928f6026a"
+  integrity sha512-TU5nlYgta8YrBMNpc9FwQzRbiXsj49gsALsXadbGHt9CROPzX5fB0rWDR5mtdpOOKa5XqRFpbj1QroPAoPzVjQ==
+  dependencies:
+    buffer "^5.5.0"
+    immediate "^3.2.3"
+    level-concat-iterator "~2.0.0"
+    level-supports "~1.0.0"
+    xtend "~4.0.0"
+
+abstract-leveldown@~6.2.1, abstract-leveldown@~6.2.3:
+  version "6.2.3"
+  resolved "https://registry.yarnpkg.com/abstract-leveldown/-/abstract-leveldown-6.2.3.tgz#036543d87e3710f2528e47040bc3261b77a9a8eb"
+  integrity sha512-BsLm5vFMRUrrLeCcRc+G0t2qOaTzpoJQLOubq2XM72eNpjF5UdU5o/5NvlNhx95XHcAvcl8OMXr4mlg/fRgUXQ==
+  dependencies:
+    buffer "^5.5.0"
+    immediate "^3.2.3"
+    level-concat-iterator "~2.0.0"
+    level-supports "~1.0.0"
+    xtend "~4.0.0"
+
 accepts@^1.3.7, accepts@~1.3.7:
   version "1.3.7"
   resolved "https://registry.yarnpkg.com/accepts/-/accepts-1.3.7.tgz#531bc726517a3b2b41f850021c6cc15eaab507cd"
@@ -3179,6 +3201,11 @@ async-foreach@^0.1.3:
   resolved "https://registry.yarnpkg.com/async-foreach/-/async-foreach-0.1.3.tgz#36121f845c0578172de419a97dbeb1d16ec34542"
   integrity sha1-NhIfhFwFeBct5Bmpfb6x0W7DRUI=
 
+async-limiter@~1.0.0:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/async-limiter/-/async-limiter-1.0.1.tgz#dd379e94f0db8310b08291f9d64c3209766617fd"
+  integrity sha512-csOlWGAcRFJaI6m+F2WKdnMKr4HhdhFVBk0H/QbJFMCr+uO2kwohwXQPxw/9OCxp05r5ghVBFSyioixx3gfkNQ==
+
 async@^2.6.2:
   version "2.6.3"
   resolved "https://registry.yarnpkg.com/async/-/async-2.6.3.tgz#d72625e2344a3656e3a3ad4fa749fa83299d82ff"
@@ -3644,7 +3671,7 @@ buffer@^4.3.0:
     ieee754 "^1.1.4"
     isarray "^1.0.0"
 
-buffer@^5.2.1, buffer@^5.5.0:
+buffer@^5.2.1, buffer@^5.5.0, buffer@^5.6.0:
   version "5.7.1"
   resolved "https://registry.yarnpkg.com/buffer/-/buffer-5.7.1.tgz#ba62e7c13133053582197160851a8f648e99eed0"
   integrity sha512-EHcyIPBQ4BSGlvjB16k5KgAJ27CIsHY/2JBmCRReo48y9rQ3MaUzWX3KVlBa4U7MyX02HdVj0K7C3WaB3ju7FQ==
@@ -5129,6 +5156,14 @@ defer-to-connect@^1.0.1:
   resolved "https://registry.yarnpkg.com/defer-to-connect/-/defer-to-connect-1.1.3.tgz#331ae050c08dcf789f8c83a7b81f0ed94f4ac591"
   integrity sha512-0ISdNousHvZT2EiFlZeZAHBUvSxmKswVCEf8hW7KWgG4a8MVEu/3Vb6uWYozkjylyCxe0JBIiRB1jV45S70WVQ==
 
+deferred-leveldown@~5.3.0:
+  version "5.3.0"
+  resolved "https://registry.yarnpkg.com/deferred-leveldown/-/deferred-leveldown-5.3.0.tgz#27a997ad95408b61161aa69bd489b86c71b78058"
+  integrity sha512-a59VOT+oDy7vtAbLRCZwWgxu2BaCfd5Hk7wxJd48ei7I+nsg8Orlb9CLG0PMZienk9BSUKgeAqkO2+Lw+1+Ukw==
+  dependencies:
+    abstract-leveldown "~6.2.1"
+    inherits "^2.0.3"
+
 define-properties@^1.1.2, define-properties@^1.1.3:
   version "1.1.3"
   resolved "https://registry.yarnpkg.com/define-properties/-/define-properties-1.1.3.tgz#cf88da6cbee26fe6db7094f61d870cbd84cee9f1"
@@ -5518,6 +5553,16 @@ encodeurl@~1.0.2:
   resolved "https://registry.yarnpkg.com/encodeurl/-/encodeurl-1.0.2.tgz#ad3ff4c86ec2d029322f5a02c3a9a606c95b3f59"
   integrity sha1-rT/0yG7C0CkyL1oCw6mmBslbP1k=
 
+encoding-down@^6.3.0:
+  version "6.3.0"
+  resolved "https://registry.yarnpkg.com/encoding-down/-/encoding-down-6.3.0.tgz#b1c4eb0e1728c146ecaef8e32963c549e76d082b"
+  integrity sha512-QKrV0iKR6MZVJV08QY0wp1e7vF6QbhnbQhb07bwpEyuz4uZiZgPlEGdkCROuFkUwdxlFaiPIhjyarH1ee/3vhw==
+  dependencies:
+    abstract-leveldown "^6.2.1"
+    inherits "^2.0.3"
+    level-codec "^9.0.0"
+    level-errors "^2.0.0"
+
 encoding@^0.1.11:
   version "0.1.13"
   resolved "https://registry.yarnpkg.com/encoding/-/encoding-0.1.13.tgz#56574afdd791f54a8e9b2785c0582a2d26210fa9"
@@ -5578,7 +5623,7 @@ err-code@^2.0.3:
   resolved "https://registry.yarnpkg.com/err-code/-/err-code-2.0.3.tgz#23c2f3b756ffdfc608d30e27c9a941024807e7f9"
   integrity sha512-2bmlRpNKBxT/CRmPOlyISQpNj+qSeYvcym/uT0Jx2bMOlKLtSy1ZmLuVxSEKKyor/N5yhvp/ZiG1oE3DEYMSFA==
 
-errno@^0.1.1, errno@^0.1.3, errno@~0.1.7:
+errno@^0.1.1, errno@^0.1.3, errno@~0.1.1, errno@~0.1.7:
   version "0.1.7"
   resolved "https://registry.yarnpkg.com/errno/-/errno-0.1.7.tgz#4684d71779ad39af177e3f007996f7c67c852618"
   integrity sha512-MfrRBDWzIWifgq6tJj60gkAwtLNb6sQPlcFrSOflcP1aFmmruKQ2wRnze/8V6kgyz7H3FF8Npzv78mZ7XLLflg==
@@ -7658,6 +7703,11 @@ imagemin@^6.1.0:
     pify "^4.0.1"
     replace-ext "^1.0.0"
 
+immediate@^3.2.3:
+  version "3.3.0"
+  resolved "https://registry.yarnpkg.com/immediate/-/immediate-3.3.0.tgz#1aef225517836bcdf7f2a2de2600c79ff0269266"
+  integrity sha512-HR7EVodfFUdQCTIeySw+WDRFJlPcLOJbXfwwZ7Oom6tjsvZ3bOkCDJHehQC3nxJrv7+f9XecwazynjU8e4Vw3Q==
+
 import-cwd@^2.0.0:
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/import-cwd/-/import-cwd-2.1.0.tgz#aa6cf36e722761285cb371ec6519f53e2435b0a9"
@@ -8586,6 +8636,88 @@ less@^3.9.0:
     native-request "^1.0.5"
     source-map "~0.6.0"
 
+level-codec@^9.0.0:
+  version "9.0.2"
+  resolved "https://registry.yarnpkg.com/level-codec/-/level-codec-9.0.2.tgz#fd60df8c64786a80d44e63423096ffead63d8cbc"
+  integrity sha512-UyIwNb1lJBChJnGfjmO0OR+ezh2iVu1Kas3nvBS/BzGnx79dv6g7unpKIDNPMhfdTEGoc7mC8uAu51XEtX+FHQ==
+  dependencies:
+    buffer "^5.6.0"
+
+level-concat-iterator@~2.0.0:
+  version "2.0.1"
+  resolved "https://registry.yarnpkg.com/level-concat-iterator/-/level-concat-iterator-2.0.1.tgz#1d1009cf108340252cb38c51f9727311193e6263"
+  integrity sha512-OTKKOqeav2QWcERMJR7IS9CUo1sHnke2C0gkSmcR7QuEtFNLLzHQAvnMw8ykvEcv0Qtkg0p7FOwP1v9e5Smdcw==
+
+level-errors@^2.0.0, level-errors@~2.0.0:
+  version "2.0.1"
+  resolved "https://registry.yarnpkg.com/level-errors/-/level-errors-2.0.1.tgz#2132a677bf4e679ce029f517c2f17432800c05c8"
+  integrity sha512-UVprBJXite4gPS+3VznfgDSU8PTRuVX0NXwoWW50KLxd2yw4Y1t2JUR5In1itQnudZqRMT9DlAM3Q//9NCjCFw==
+  dependencies:
+    errno "~0.1.1"
+
+level-iterator-stream@~4.0.0:
+  version "4.0.2"
+  resolved "https://registry.yarnpkg.com/level-iterator-stream/-/level-iterator-stream-4.0.2.tgz#7ceba69b713b0d7e22fcc0d1f128ccdc8a24f79c"
+  integrity sha512-ZSthfEqzGSOMWoUGhTXdX9jv26d32XJuHz/5YnuHZzH6wldfWMOVwI9TBtKcya4BKTyTt3XVA0A3cF3q5CY30Q==
+  dependencies:
+    inherits "^2.0.4"
+    readable-stream "^3.4.0"
+    xtend "^4.0.2"
+
+level-js@^5.0.0:
+  version "5.0.2"
+  resolved "https://registry.yarnpkg.com/level-js/-/level-js-5.0.2.tgz#5e280b8f93abd9ef3a305b13faf0b5397c969b55"
+  integrity sha512-SnBIDo2pdO5VXh02ZmtAyPP6/+6YTJg2ibLtl9C34pWvmtMEmRTWpra+qO/hifkUtBTOtfx6S9vLDjBsBK4gRg==
+  dependencies:
+    abstract-leveldown "~6.2.3"
+    buffer "^5.5.0"
+    inherits "^2.0.3"
+    ltgt "^2.1.2"
+
+level-packager@^5.1.0:
+  version "5.1.1"
+  resolved "https://registry.yarnpkg.com/level-packager/-/level-packager-5.1.1.tgz#323ec842d6babe7336f70299c14df2e329c18939"
+  integrity sha512-HMwMaQPlTC1IlcwT3+swhqf/NUO+ZhXVz6TY1zZIIZlIR0YSn8GtAAWmIvKjNY16ZkEg/JcpAuQskxsXqC0yOQ==
+  dependencies:
+    encoding-down "^6.3.0"
+    levelup "^4.3.2"
+
+level-supports@~1.0.0:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/level-supports/-/level-supports-1.0.1.tgz#2f530a596834c7301622521988e2c36bb77d122d"
+  integrity sha512-rXM7GYnW8gsl1vedTJIbzOrRv85c/2uCMpiiCzO2fndd06U/kUXEEU9evYn4zFggBOg36IsBW8LzqIpETwwQzg==
+  dependencies:
+    xtend "^4.0.2"
+
+level@^6.0.1:
+  version "6.0.1"
+  resolved "https://registry.yarnpkg.com/level/-/level-6.0.1.tgz#dc34c5edb81846a6de5079eac15706334b0d7cd6"
+  integrity sha512-psRSqJZCsC/irNhfHzrVZbmPYXDcEYhA5TVNwr+V92jF44rbf86hqGp8fiT702FyiArScYIlPSBTDUASCVNSpw==
+  dependencies:
+    level-js "^5.0.0"
+    level-packager "^5.1.0"
+    leveldown "^5.4.0"
+
+leveldown@^5.4.0:
+  version "5.6.0"
+  resolved "https://registry.yarnpkg.com/leveldown/-/leveldown-5.6.0.tgz#16ba937bb2991c6094e13ac5a6898ee66d3eee98"
+  integrity sha512-iB8O/7Db9lPaITU1aA2txU/cBEXAt4vWwKQRrrWuS6XDgbP4QZGj9BL2aNbwb002atoQ/lIotJkfyzz+ygQnUQ==
+  dependencies:
+    abstract-leveldown "~6.2.1"
+    napi-macros "~2.0.0"
+    node-gyp-build "~4.1.0"
+
+levelup@^4.3.2:
+  version "4.4.0"
+  resolved "https://registry.yarnpkg.com/levelup/-/levelup-4.4.0.tgz#f89da3a228c38deb49c48f88a70fb71f01cafed6"
+  integrity sha512-94++VFO3qN95cM/d6eBXvd894oJE0w3cInq9USsyQzzoJxmiYzPAocNcuGCPGGjoXqDVJcr3C1jzt1TSjyaiLQ==
+  dependencies:
+    deferred-leveldown "~5.3.0"
+    level-errors "~2.0.0"
+    level-iterator-stream "~4.0.0"
+    level-supports "~1.0.0"
+    xtend "~4.0.0"
+
 leven@^3.1.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/leven/-/leven-3.1.0.tgz#77891de834064cccba82ae7842bb6b14a13ed7f2"
@@ -8606,7 +8738,7 @@ levn@^0.4.1:
     prelude-ls "^1.2.1"
     type-check "~0.4.0"
 
-lib0@^0.2.12, lib0@^0.2.28, lib0@^0.2.32, lib0@^0.2.33, lib0@^0.2.34:
+lib0@^0.2.12, lib0@^0.2.28, lib0@^0.2.31, lib0@^0.2.32, lib0@^0.2.33, lib0@^0.2.34:
   version "0.2.34"
   resolved "https://registry.yarnpkg.com/lib0/-/lib0-0.2.34.tgz#c4479f5f2083894687fcfa9d0b9d9935e35ea008"
   integrity sha512-cqsVIMPgFlDtgQcpkt7HOY6W3sbYPIe3qxMnbRSwHTgiQancgm+TRDPx28mC6GUZ6lG6Nr0bIWf4Nog6dWUNUg==
@@ -8770,6 +8902,11 @@ lodash.clonedeep@^4.5.0:
   resolved "https://registry.yarnpkg.com/lodash.clonedeep/-/lodash.clonedeep-4.5.0.tgz#e23f3f9c4f8fbdde872529c1071857a086e5ccef"
   integrity sha1-4j8/nE+Pvd6HJSnBBxhXoIblzO8=
 
+lodash.debounce@^4.0.8:
+  version "4.0.8"
+  resolved "https://registry.yarnpkg.com/lodash.debounce/-/lodash.debounce-4.0.8.tgz#82d79bff30a67c4005ffd5e2515300ad9ca4d7af"
+  integrity sha1-gteb/zCmfEAF/9XiUVMArZyk168=
+
 lodash.deburr@^4.1.0:
   version "4.1.0"
   resolved "https://registry.yarnpkg.com/lodash.deburr/-/lodash.deburr-4.1.0.tgz#ddb1bbb3ef07458c0177ba07de14422cb033ff9b"
@@ -8950,6 +9087,11 @@ lru-cache@^6.0.0:
   dependencies:
     yallist "^4.0.0"
 
+ltgt@^2.1.2:
+  version "2.2.1"
+  resolved "https://registry.yarnpkg.com/ltgt/-/ltgt-2.2.1.tgz#f35ca91c493f7b73da0e07495304f17b31f87ee5"
+  integrity sha1-81ypHEk/e3PaDgdJUwTxezH4fuU=
+
 lunr@^2.3.9:
   version "2.3.9"
   resolved "https://registry.yarnpkg.com/lunr/-/lunr-2.3.9.tgz#18b123142832337dd6e964df1a5a7707b25d35e1"
@@ -9566,6 +9708,11 @@ napi-build-utils@^1.0.1:
   resolved "https://registry.yarnpkg.com/napi-build-utils/-/napi-build-utils-1.0.2.tgz#b1fddc0b2c46e380a0b7a76f984dd47c41a13806"
   integrity sha512-ONmRUqK7zj7DWX0D9ADe03wbwOBZxNAfF20PlGfCWQcD3+/MakShIHrMqx9YwPTfxDdF1zLeL+RGZiR9kGMLdg==
 
+napi-macros@~2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/napi-macros/-/napi-macros-2.0.0.tgz#2b6bae421e7b96eb687aa6c77a7858640670001b"
+  integrity sha512-A0xLykHtARfueITVDernsAWdtIMbOJgKgcluwENp3AlsKN/PloyO10HtmoqnFAQAcxPkgZN7wdfPfEd0zNGxbg==
+
 native-request@^1.0.5:
   version "1.0.8"
   resolved "https://registry.yarnpkg.com/native-request/-/native-request-1.0.8.tgz#8f66bf606e0f7ea27c0e5995eb2f5d03e33ae6fb"
@@ -9637,6 +9784,11 @@ node-fetch@^2.5.0, node-fetch@^2.6.1:
   resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-2.6.1.tgz#045bd323631f76ed2e2b55573394416b639a0052"
   integrity sha512-V4aYg89jEoVRxRb2fJdAg8FHvI7cEyYdVAh94HH0UIK8oJxUfkjlDQN9RbMx+bEjP7+ggMiFRprSti032Oipxw==
 
+node-gyp-build@~4.1.0:
+  version "4.1.1"
+  resolved "https://registry.yarnpkg.com/node-gyp-build/-/node-gyp-build-4.1.1.tgz#d7270b5d86717068d114cc57fff352f96d745feb"
+  integrity sha512-dSq1xmcPDKPZ2EED2S6zw/b9NKsqzXRE6dVr8TVQnI3FJOTteUMuqF3Qqs6LZg+mLGYJWqQzMbIjMtJqTv87nQ==
+
 node-gyp@^5.0.2:
   version "5.1.1"
   resolved "https://registry.yarnpkg.com/node-gyp/-/node-gyp-5.1.1.tgz#eb915f7b631c937d282e33aed44cb7a025f62a3e"
@@ -14742,6 +14894,13 @@ write@1.0.3:
   dependencies:
     mkdirp "^0.5.1"
 
+ws@^6.2.1:
+  version "6.2.1"
+  resolved "https://registry.yarnpkg.com/ws/-/ws-6.2.1.tgz#442fdf0a47ed64f59b6a5d8ff130f4748ed524fb"
+  integrity sha512-GIyAXC2cB7LjvpgMt9EKS2ldqr0MTrORaleiOno6TweZ6r3TKtoFQWay/2PceJ3RuBasOHzXNn5Lrw1X0bEjqA==
+  dependencies:
+    async-limiter "~1.0.0"
+
 ws@^7.2.0:
   version "7.4.0"
   resolved "https://registry.yarnpkg.com/ws/-/ws-7.4.0.tgz#a5dd76a24197940d4a8bb9e0e152bb4503764da7"
@@ -14765,7 +14924,7 @@ xss@^1.0.6:
     commander "^2.20.3"
     cssfilter "0.0.10"
 
-xtend@^4.0.0, xtend@^4.0.1, xtend@~4.0.1:
+xtend@^4.0.0, xtend@^4.0.1, xtend@^4.0.2, xtend@~4.0.0, xtend@~4.0.1:
   version "4.0.2"
   resolved "https://registry.yarnpkg.com/xtend/-/xtend-4.0.2.tgz#bb72779f5fa465186b1f438f674fa347fdb5db54"
   integrity sha512-LKYU1iAXJXUgAXn9URjiu+MWhyUXHsvfp7mcuYm9dSUKK0/CjtrUwFAxD82/mCWbtLsGjFIad0wIsod4zrTAEQ==
@@ -14777,6 +14936,14 @@ y-indexeddb@^9.0.5:
   dependencies:
     lib0 "^0.2.12"
 
+y-leveldb@^0.1.0:
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/y-leveldb/-/y-leveldb-0.1.0.tgz#8b60c1af020252445875ebc70d52666017bcb038"
+  integrity sha512-sMuitVrsAUNh+0b66I42nAuW3lCmez171uP4k0ePcTAJ+c+Iw9w4Yq3wwiyrDMFXBEyQSjSF86Inc23wEvWnxw==
+  dependencies:
+    level "^6.0.1"
+    lib0 "^0.2.31"
+
 y-prosemirror@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/y-prosemirror/-/y-prosemirror-1.0.0.tgz#a3d0a36726355979a8e88814c40851851e5bf241"
@@ -14802,6 +14969,18 @@ y-webrtc@^10.1.6:
   optionalDependencies:
     ws "^7.2.0"
 
+y-websocket@^1.3.6:
+  version "1.3.6"
+  resolved "https://registry.yarnpkg.com/y-websocket/-/y-websocket-1.3.6.tgz#bafe1a92dc555a71ac18e6f63b0409957d061d6c"
+  integrity sha512-b4V/xw7l0NN6E7FTLEXayHq67QQA2UoXH/y48gvd6L7wQApnB84tg6t3Wo/aXtby1x02G5J3moN+4k+IIQsCDQ==
+  dependencies:
+    lib0 "^0.2.31"
+    lodash.debounce "^4.0.8"
+    y-leveldb "^0.1.0"
+    y-protocols "^1.0.0"
+  optionalDependencies:
+    ws "^6.2.1"
+
 y18n@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/y18n/-/y18n-4.0.0.tgz#95ef94f85ecc81d007c264e190a120f0a3c8566b"