diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
new file mode 100644
index 0000000..1a9075b
--- /dev/null
+++ b/.github/workflows/main.yml
@@ -0,0 +1,22 @@
+name: CI
+on:
+    - push
+    - pull_request
+jobs:
+    test:
+        name: Tests on node.js ${{ matrix.node-version }}
+        runs-on: ubuntu-latest
+        strategy:
+            fail-fast: false
+            matrix:
+                node-version:
+                    - 15
+                    - 14
+                    - 12
+        steps:
+            - uses: actions/checkout@v2
+            - uses: actions/setup-node@v1
+              with:
+                  node-version: ${{ matrix.node-version }}
+            - run: npm install
+            - run: npm test
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index c7b016c..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,3 +0,0 @@
-language: node_js
-node_js:
-  - 12
diff --git a/README.md b/README.md
index 7544ce3..c4f7760 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # whynot.js
 
 [![NPM version](https://badge.fury.io/js/whynot.svg)](https://badge.fury.io/js/whynot)
-[![Build Status](https://travis-ci.org/bwrrp/whynot.js.svg?branch=master)](https://travis-ci.org/bwrrp/whynot.js)
+[![CI](https://github.com/bwrrp/whynot.js/workflows/CI/badge.svg)](https://github.com/bwrrp/whynot.js/actions?query=workflow%3ACI)
 
 Generic VM-based formal language matching framework, inspired by [http://swtch.com/~rsc/regexp/](http://swtch.com/~rsc/regexp/)
 
@@ -14,7 +14,7 @@ language's grammar. This enables giving feedback on _why_ a given input does
 not match the grammar rules in some way.
 
 For an example showing how this library can be used, see
-[Examples.tests.ts](https://github.com/bwrrp/whynot.js/blob/master/test/Examples.tests.ts)
+[Examples.tests.ts](https://github.com/bwrrp/whynot.js/blob/main/test/Examples.tests.ts)
 in the test suite.
 
 ## Benchmarking
diff --git a/api/whynot.api.json b/api/whynot.api.json
index 21a1251..af864e4 100644
--- a/api/whynot.api.json
+++ b/api/whynot.api.json
@@ -1,7 +1,7 @@
 {
   "metadata": {
     "toolPackage": "@microsoft/api-extractor",
-    "toolVersion": "7.9.22",
+    "toolVersion": "7.13.1",
     "schemaVersion": 1003,
     "oldestForwardsCompatibleVersion": 1001
   },
@@ -142,6 +142,7 @@
                   "text": ";"
                 }
               ],
+              "isOptional": false,
               "isStatic": false,
               "returnTypeTokenRange": {
                 "startIndex": 1,
@@ -183,6 +184,7 @@
                   "text": ";"
                 }
               ],
+              "isOptional": false,
               "isStatic": false,
               "returnTypeTokenRange": {
                 "startIndex": 3,
@@ -237,6 +239,7 @@
                   "text": ";"
                 }
               ],
+              "isOptional": false,
               "isStatic": false,
               "returnTypeTokenRange": {
                 "startIndex": 4,
@@ -286,6 +289,7 @@
                   "text": ";"
                 }
               ],
+              "isOptional": false,
               "isStatic": false,
               "returnTypeTokenRange": {
                 "startIndex": 3,
@@ -327,6 +331,7 @@
                   "text": ";"
                 }
               ],
+              "isOptional": false,
               "releaseTag": "Public",
               "name": "program",
               "propertyTypeTokenRange": {
@@ -379,6 +384,7 @@
                   "text": ";"
                 }
               ],
+              "isOptional": false,
               "isStatic": false,
               "returnTypeTokenRange": {
                 "startIndex": 6,
@@ -461,6 +467,7 @@
                   "text": ";"
                 }
               ],
+              "isOptional": false,
               "isStatic": false,
               "returnTypeTokenRange": {
                 "startIndex": 6,
@@ -727,6 +734,7 @@
                   "text": ";"
                 }
               ],
+              "isOptional": false,
               "isStatic": false,
               "returnTypeTokenRange": {
                 "startIndex": 5,
diff --git a/package.json b/package.json
index 9513a26..d0b8bd2 100644
--- a/package.json
+++ b/package.json
@@ -35,27 +35,27 @@
 	},
 	"devDependencies": {
 		"@fontoxml/fonto-benchmark-runner": "0.1.0",
-		"@microsoft/api-documenter": "^7.8.56",
-		"@microsoft/api-extractor": "^7.9.22",
-		"@rollup/plugin-commonjs": "^15.1.0",
-		"@rollup/plugin-node-resolve": "^9.0.0",
+		"@microsoft/api-documenter": "^7.12.7",
+		"@microsoft/api-extractor": "^7.13.1",
+		"@rollup/plugin-commonjs": "^17.1.0",
+		"@rollup/plugin-node-resolve": "^11.1.1",
 		"@types/glob": "^7.1.3",
-		"@types/jest": "^26.0.14",
-		"@types/node-static": "^0.7.5",
+		"@types/jest": "^26.0.20",
+		"@types/node-static": "^0.7.6",
 		"concurrently": "^5.3.0",
-		"copyfiles": "^2.3.0",
+		"copyfiles": "^2.4.1",
 		"glob": "^7.1.6",
-		"jest": "^26.4.2",
+		"jest": "^26.6.3",
 		"node-static": "^0.7.11",
 		"npm-run-all": "^4.1.5",
-		"prettier": "^2.1.2",
-		"prsc": "^1.1.0",
+		"prettier": "^2.2.1",
+		"prsc": "^2.0.1",
 		"rimraf": "^3.0.2",
-		"rollup": "^2.28.2",
-		"rollup-plugin-sourcemaps": "^0.6.2",
+		"rollup": "^2.38.5",
+		"rollup-plugin-sourcemaps": "^0.6.3",
 		"rollup-plugin-terser": "^7.0.2",
-		"ts-jest": "~26.4.0",
-		"typescript": "^4.0.3"
+		"ts-jest": "~26.5.0",
+		"typescript": "^4.1.3"
 	},
 	"jest": {
 		"transform": {