diff --git a/.prettierignore b/.prettierignore
index ab1e283..85bb9e9 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -2,5 +2,9 @@ node_modules/
 out/
 package-lock.json
 
+# Ignore code generated into our project by langium based on our grammar.
+generated/
+syntaxes/
+
 # Ignore examples for now because they have syntax errors we're testing, prettier can't parse them.
 examples/
diff --git a/bin/cli b/bin/cli
deleted file mode 100755
index f0a5258..0000000
--- a/bin/cli
+++ /dev/null
@@ -1,3 +0,0 @@
-#!/usr/bin/env node
-
-require("../out/cli").default();
\ No newline at end of file
diff --git a/bin/cli.js b/bin/cli.js
new file mode 100755
index 0000000..1838fbf
--- /dev/null
+++ b/bin/cli.js
@@ -0,0 +1,3 @@
+#!/usr/bin/env node
+
+require('../out/cli/index.js').default()
diff --git a/examples/st.d.ts b/examples/st.d.ts
new file mode 100644
index 0000000..ed36d7e
--- /dev/null
+++ b/examples/st.d.ts
@@ -0,0 +1,3 @@
+type i32 = number;
+type f32 = number;
+type f64 = number;
diff --git a/examples/tsconfig.json b/examples/tsconfig.json
new file mode 100644
index 0000000..e0ae827
--- /dev/null
+++ b/examples/tsconfig.json
@@ -0,0 +1,24 @@
+{
+	"compilerOptions": {
+		// Compiler setup
+		"target": "ES6",
+		"module": "esnext",
+		"lib": ["ESNext"],
+		"sourceMap": true,
+		"outDir": "out",
+		"moduleResolution": "node",
+		"esModuleInterop": true,
+		"skipLibCheck": true,
+		"forceConsistentCasingInFileNames": true,
+
+		// Type checking
+		"strict": true,
+		"noUnusedLocals": true,
+		"noImplicitReturns": true,
+		"noImplicitOverride": true,
+
+		"importsNotUsedAsValues": "error"
+	},
+	"include": ["./**/*.ts"],
+	"exclude": ["out", "node_modules"]
+}
diff --git a/package.json b/package.json
index 731ed8d..c29e683 100644
--- a/package.json
+++ b/package.json
@@ -41,7 +41,7 @@
 		"src"
 	],
 	"bin": {
-		"bytescript-cli": "./bin/cli"
+		"bs": "./bin/cli.js"
 	},
 	"main": "./out/extension.js",
 	"scripts": {
@@ -53,9 +53,11 @@
 		"langium:watch": "langium generate --watch",
 		"format:all": "prettier --write .",
 		"wat2wasm": "wat2wasm generated/poc1.wat -o generated/poc1.wasm",
-		"test": "npm run test:compile && npm run test:node && echo 'Tests passed!'",
-		"test:compile": "./bin/cli compile examples/basic/poc1.ts && npm run wat2wasm",
-		"test:node": "node tests/node/test.mjs"
+		"wtr": "web-test-runner tests/browser/*.ts --node-resolve",
+		"test": "npm run lint && npm run test:compile && npm run test:node && npm run test:browser && echo 'Tests passed!'",
+		"test:compile": "./bin/cli.js compile examples/basic/poc1.ts && npm run wat2wasm",
+		"test:node": "node tests/node/test.mjs",
+		"test:browser": "npm run wtr"
 	},
 	"dependencies": {
 		"chalk": "^4.1.2",
@@ -64,13 +66,17 @@
 		"langium": "~1.0.0",
 		"vscode-languageclient": "^8.0.2",
 		"vscode-languageserver": "^8.0.2",
-		"vscode-uri": "^3.0.2"
+		"vscode-uri": "^3.0.2",
+		"wdeasync": "^0.1.118"
 	},
 	"devDependencies": {
+		"@open-wc/testing": "^3.1.8",
 		"@types/node": "^14.17.3",
 		"@types/vscode": "^1.56.0",
 		"@typescript-eslint/eslint-plugin": "^5.28.0",
 		"@typescript-eslint/parser": "^5.28.0",
+		"@web/dev-server-esbuild": "^0.4.1",
+		"@web/test-runner": "^0.16.1",
 		"binaryen": "^113.0.0",
 		"eslint": "^8.17.0",
 		"langium-cli": "~1.0.0",
diff --git a/src/cli/cli-util.ts b/src/cli/cli-util.ts
index d41099b..d759e51 100644
--- a/src/cli/cli-util.ts
+++ b/src/cli/cli-util.ts
@@ -2,7 +2,9 @@ import chalk from 'chalk'
 import path from 'path'
 import fs from 'fs'
 import type {AstNode, LangiumDocument, LangiumServices} from 'langium'
-import {URI} from 'vscode-uri'
+import * as vscodeUri from 'vscode-uri'
+
+const {URI} = vscodeUri
 
 export async function extractDocument(fileName: string, services: LangiumServices): Promise<LangiumDocument> {
 	const extensions = services.LanguageMetaData.fileExtensions
diff --git a/src/cli/generator.ts b/src/cli/generator.ts
index 0f8001e..e1f0c02 100644
--- a/src/cli/generator.ts
+++ b/src/cli/generator.ts
@@ -7,12 +7,12 @@ import {
 	isExportedFunctionDeclaration,
 	isOriginalFunctionDeclaration,
 	isReturnStatement,
-} from '../language-server/generated/ast'
-import {extractDestinationAndName} from './cli-util'
-import {isBinaryExpressionSum} from '../language-server/types/types'
-import {getType} from '../language-server/types/types'
-import {isI32NumberType} from '../language-server/types/descriptions'
-import {isBinaryExpressionProduct} from '../language-server/types/types'
+} from '../language-server/generated/ast.js'
+import {extractDestinationAndName} from './cli-util.js'
+import {isBinaryExpressionSum} from '../language-server/types/types.js'
+import {getType} from '../language-server/types/types.js'
+import {isI32NumberType} from '../language-server/types/descriptions.js'
+import {isBinaryExpressionProduct} from '../language-server/types/types.js'
 
 export function generateWasm(topLevel: TopLevel, filePath: string, destination: string | undefined): string {
 	const data = extractDestinationAndName(filePath, destination)
diff --git a/src/cli/index.ts b/src/cli/index.ts
index 87f0acf..754dfa9 100644
--- a/src/cli/index.ts
+++ b/src/cli/index.ts
@@ -1,17 +1,20 @@
-import chalk from 'chalk'
+import {green} from 'chalk'
 import {Command} from 'commander'
-import type {TopLevel} from '../language-server/generated/ast'
-import {ByteScriptLanguageMetaData} from '../language-server/generated/module'
-import {createByteScriptServices} from '../language-server/bytescript-module'
-import {extractAstNode} from './cli-util'
-import {generateWasm} from './generator'
-import {NodeFileSystem} from 'langium/node'
+import type {TopLevel} from '../language-server/generated/ast.js'
+import {ByteScriptLanguageMetaData} from '../language-server/generated/module.js'
+import {createByteScriptServices} from '../language-server/bytescript-module.js'
+import {extractAstNode} from './cli-util.js'
+import {generateWasm} from './generator.js'
+import {NodeFileSystem} from 'langium/node.js'
+
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const pkg = require('../../package.json')
 
 export async function generate(fileName: string, opts: GenerateOptions): Promise<void> {
 	const services = createByteScriptServices(NodeFileSystem).ByteScript
 	const ast = await extractAstNode<TopLevel>(fileName, services)
 	const generatedFilePath = generateWasm(ast, fileName, opts.destination)
-	console.log(chalk.green(`Build successful: ${generatedFilePath}`))
+	console.log(green(`Build successful: ${generatedFilePath}`))
 }
 
 export type GenerateOptions = {
@@ -21,9 +24,7 @@ export type GenerateOptions = {
 export default function (): void {
 	const program = new Command()
 
-	program
-		// eslint-disable-next-line @typescript-eslint/no-var-requires
-		.version(require('../../package.json').version)
+	program.version(pkg.version)
 
 	const fileExtensions = ByteScriptLanguageMetaData.fileExtensions.join(', ')
 	program
diff --git a/src/extension.ts b/src/extension.ts
index df13b98..70faf91 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -1,6 +1,6 @@
 import * as vscode from 'vscode'
 import * as path from 'path'
-import {LanguageClient, LanguageClientOptions, ServerOptions, TransportKind} from 'vscode-languageclient/node'
+import {LanguageClient, LanguageClientOptions, ServerOptions, TransportKind} from 'vscode-languageclient/node.js'
 
 let client: LanguageClient
 
diff --git a/src/language-server/bytescript-module.ts b/src/language-server/bytescript-module.ts
index b2df9f6..49cf62a 100644
--- a/src/language-server/bytescript-module.ts
+++ b/src/language-server/bytescript-module.ts
@@ -8,9 +8,9 @@ import {
 	Module,
 	PartialLangiumServices,
 } from 'langium'
-import {ByteScriptGeneratedModule, ByteScriptGeneratedSharedModule} from './generated/module'
-import {ByteScriptValidator, registerValidationChecks} from './bytescript-validator'
-import {ByteScriptScopeProvider} from './bytescript-scope'
+import {ByteScriptGeneratedModule, ByteScriptGeneratedSharedModule} from './generated/module.js'
+import {ByteScriptValidator, registerValidationChecks} from './bytescript-validator.js'
+import {ByteScriptScopeProvider} from './bytescript-scope.js'
 
 /**
  * Declaration of custom services - add your own service classes here.
diff --git a/src/language-server/bytescript-scope.ts b/src/language-server/bytescript-scope.ts
new file mode 100644
index 0000000..2f0e23f
--- /dev/null
+++ b/src/language-server/bytescript-scope.ts
@@ -0,0 +1,6 @@
+import {DefaultScopeProvider} from 'langium'
+
+export class ByteScriptScopeProvider extends DefaultScopeProvider {
+	// TODO we'll need to fill this in to provide scope for some cases, but the
+	// DefaultScopeProvider is currently good enough for the initial PoC.
+}
diff --git a/src/language-server/bytescript-validator.ts b/src/language-server/bytescript-validator.ts
index e7aafac..31f04cf 100644
--- a/src/language-server/bytescript-validator.ts
+++ b/src/language-server/bytescript-validator.ts
@@ -14,16 +14,16 @@ import {
 	Block,
 	ArrowReturnExpression,
 	TypeDeclaration,
-} from './generated/ast'
-import type {ByteScriptServices} from './bytescript-module'
+} from './generated/ast.js'
+import type {ByteScriptServices} from './bytescript-module.js'
 import {
 	getType,
 	isAssignable,
 	isBinaryExpressionAssignment,
 	isBinaryExpressionProduct,
 	isBinaryExpressionSum,
-} from './types/types'
-import {TypeInferenceError, isTypeInferenceError, TypeDescription, typeToString} from './types/descriptions'
+} from './types/types.js'
+import {TypeInferenceError, isTypeInferenceError, TypeDescription, typeToString} from './types/descriptions.js'
 
 /**
  * Register custom validation checks.
diff --git a/src/language-server/main.ts b/src/language-server/main.ts
index ce794bc..b1bec22 100644
--- a/src/language-server/main.ts
+++ b/src/language-server/main.ts
@@ -1,7 +1,7 @@
 import {startLanguageServer} from 'langium'
-import {NodeFileSystem} from 'langium/node'
-import {createConnection, ProposedFeatures} from 'vscode-languageserver/node'
-import {createByteScriptServices} from './bytescript-module'
+import {NodeFileSystem} from 'langium/node.js'
+import {createConnection, ProposedFeatures} from 'vscode-languageserver/node.js'
+import {createByteScriptServices} from './bytescript-module.js'
 
 // Create a connection to the client
 const connection = createConnection(ProposedFeatures.all)
diff --git a/src/language-server/types/descriptions.ts b/src/language-server/types/descriptions.ts
index 90ed427..a55f108 100644
--- a/src/language-server/types/descriptions.ts
+++ b/src/language-server/types/descriptions.ts
@@ -1,5 +1,5 @@
 import type {AstNode} from 'langium'
-import type {Identifier, NumberLiteral, TypeExpression} from '../generated/ast'
+import type {Identifier, NumberLiteral, TypeExpression} from '../generated/ast.js'
 
 export type TypeDescription = NumberType | FunctionType | TypeInferenceError
 
diff --git a/src/language-server/types/types.ts b/src/language-server/types/types.ts
index daf3387..e58070c 100644
--- a/src/language-server/types/types.ts
+++ b/src/language-server/types/types.ts
@@ -13,7 +13,7 @@ import {
 	isIdentifier,
 	isBinaryExpression,
 	isParameter,
-} from '../generated/ast'
+} from '../generated/ast.js'
 import {
 	createTypeInferenceError,
 	createF64NumberType,
@@ -22,7 +22,7 @@ import {
 	createLiteralNumberType,
 	FunctionTypeParameter,
 	TypeDescription,
-} from './descriptions'
+} from './descriptions.js'
 
 const types = new Map<AstNode, TypeDescription>()
 
diff --git a/tests/browser/test.ts b/tests/browser/test.ts
new file mode 100644
index 0000000..4442717
--- /dev/null
+++ b/tests/browser/test.ts
@@ -0,0 +1,12 @@
+import {expect} from '@open-wc/testing'
+
+describe('poc1', () => {
+	it('add sums up 2 numbers', async () => {
+		const wasmModule = await WebAssembly.instantiateStreaming(await fetch('/generated/poc1.wasm'))
+
+		const {add} = wasmModule.instance.exports as {add(a: number, b: number): number}
+
+		expect(add(1, 1)).to.equal(2)
+		expect(add(3, 12)).to.equal(15)
+	})
+})
diff --git a/tests/node/test.mjs b/tests/node/test.mjs
index 7bdec28..4cbd40d 100644
--- a/tests/node/test.mjs
+++ b/tests/node/test.mjs
@@ -8,3 +8,5 @@ const {add} = wasmModule.instance.exports
 const sum = add(5, 6)
 
 console.assert(sum === 11, 'expected 5+6 = 11')
+
+console.log('Node test passed!')
diff --git a/web-test-runner.config.mjs b/web-test-runner.config.mjs
new file mode 100644
index 0000000..c8179f6
--- /dev/null
+++ b/web-test-runner.config.mjs
@@ -0,0 +1,5 @@
+import {esbuildPlugin} from '@web/dev-server-esbuild'
+
+export default {
+	plugins: [esbuildPlugin({ts: true})],
+}