diff --git a/src/server.ts b/src/server.ts
index 525504c..2b291df 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -15,6 +15,7 @@ import { FoldingService } from "./services/folding";
 import { RenamingService } from "./services/renaming";
 import { FindReferencesService } from "./services/find-references";
 import { GoToDefinitionService } from "./services/go-to-definition";
+import { FormattingService } from "./services/formatting";
 
 export interface LanguageService {
   activate(connection: IConnection, documents: TextDocuments): void;
@@ -29,6 +30,7 @@ const services: ReadonlyArray<LanguageService> = [
   new DiagnosticsService(),
   new FindReferencesService(),
   new FoldingService(),
+  new FormattingService(),
   new GoToDefinitionService(),
   new RenamingService(),
 ];
diff --git a/src/services/formatting.ts b/src/services/formatting.ts
new file mode 100644
index 0000000..e23d51f
--- /dev/null
+++ b/src/services/formatting.ts
@@ -0,0 +1,125 @@
+/*!
+ * Copyright 2019 Omar Tawfik. Please see LICENSE file at the root of this repository.
+ */
+
+import { IConnection, TextDocuments, ServerCapabilities, TextEdit, Range } from "vscode-languageserver";
+import { LanguageService } from "../server";
+import { accessCache } from "../util/cache";
+import { Compilation } from "../util/compilation";
+import { Token, TokenKind } from "../scanning/tokens";
+
+export class FormattingService implements LanguageService {
+  public fillCapabilities(capabilities: ServerCapabilities): void {
+    capabilities.documentFormattingProvider = true;
+  }
+
+  public activate(connection: IConnection, documents: TextDocuments): void {
+    connection.onDocumentFormatting(params => {
+      const { uri } = params.textDocument;
+      const compilation = accessCache(documents, uri);
+
+      const { insertSpaces, tabSize } = params.options;
+      const indentation = insertSpaces ? " ".repeat(tabSize) : "\t";
+
+      const result = FormattingService.format(compilation, indentation);
+      const fullRange = Range.create(0, 0, Number.MAX_SAFE_INTEGER, Number.MAX_SAFE_INTEGER);
+      return [TextEdit.replace(fullRange, result)];
+    });
+  }
+
+  public static format(compilation: Compilation, indentationValue: string): string {
+    const lines = Array<FormattingLine>();
+    let indentationLevel = 0;
+
+    for (const token of compilation.tokens) {
+      const lineIndex = token.range.start.line;
+      while (lines.length < lineIndex) {
+        lines.push(new FormattingLine(indentationLevel));
+      }
+
+      switch (token.kind) {
+        case TokenKind.RightCurlyBracket:
+        case TokenKind.RightSquareBracket: {
+          indentationLevel -= 1;
+          break;
+        }
+      }
+
+      if (lines.length === lineIndex) {
+        lines.push(new FormattingLine(indentationLevel));
+      }
+
+      lines[lineIndex].add(token);
+
+      switch (token.kind) {
+        case TokenKind.LeftCurlyBracket:
+        case TokenKind.LeftSquareBracket: {
+          indentationLevel += 1;
+          break;
+        }
+      }
+    }
+
+    lines.push(new FormattingLine(0));
+    return lines.map(line => line.format(indentationValue)).join(compilation.text.includes("\r\n") ? "\r\n" : "\n");
+  }
+}
+
+class FormattingLine {
+  private readonly tokens = Array<Token>();
+
+  public constructor(private readonly indentationLevel: number) {}
+
+  public add(token: Token): void {
+    this.tokens.push(token);
+  }
+
+  public format(indentationValue: string): string {
+    let result = indentationValue.repeat(this.indentationLevel);
+
+    function append(value: string): void {
+      if (value.trim() || result.trim()) {
+        result += value;
+      }
+    }
+
+    for (const token of this.tokens) {
+      switch (token.kind) {
+        case TokenKind.VersionKeyword:
+        case TokenKind.WorkflowKeyword:
+        case TokenKind.ActionKeyword:
+        case TokenKind.OnKeyword:
+        case TokenKind.ResolvesKeyword:
+        case TokenKind.UsesKeyword:
+        case TokenKind.NeedsKeyword:
+        case TokenKind.RunsKeyword:
+        case TokenKind.ArgsKeyword:
+        case TokenKind.EnvKeyword:
+        case TokenKind.SecretsKeyword:
+        case TokenKind.Equal:
+        case TokenKind.Identifier:
+        case TokenKind.IntegerLiteral:
+        case TokenKind.StringLiteral:
+        case TokenKind.Unrecognized:
+        case TokenKind.Comment:
+        case TokenKind.LeftCurlyBracket:
+        case TokenKind.LeftSquareBracket:
+        case TokenKind.RightCurlyBracket:
+        case TokenKind.RightSquareBracket: {
+          append(" ");
+          append(token.text);
+          break;
+        }
+        case TokenKind.Comma: {
+          append(token.text);
+          break;
+        }
+        default: {
+          throw new Error(`Unexpected token kind '${token.kind}'`);
+        }
+      }
+    }
+
+    return result.trimRight();
+  }
+}
diff --git a/test/formatting.spec.ts b/test/formatting.spec.ts
new file mode 100644
index 0000000..97add8d
--- /dev/null
+++ b/test/formatting.spec.ts
@@ -0,0 +1,73 @@
+/*!
+ * Copyright 2019 Omar Tawfik. Please see LICENSE file at the root of this repository.
+ */
+
+import { Compilation } from "../src/util/compilation";
+import { FormattingService } from "../src/services/formatting";
+
+describe(__filename, () => {
+  it("formats a one line empty action", () => {
+    expectFormatting(`
+action"x"{}
+`).toMatchInlineSnapshot(`
+"
+action \\"x\\" { }
+"
+`);
+  });
+
+  it("formats a one line action with properties", () => {
+    expectFormatting(`
+action "x" { uses="./ci" }
+`).toMatchInlineSnapshot(`
+"
+action \\"x\\" { uses = \\"./ci\\" }
+"
+`);
+  });
+
+  it("formats an action with embedded comments", () => {
+    expectFormatting(`
+# on start of line
+          # should be aligned to start
+action "x" {
+    # should be indented
+                uses="./ci" // should be at end
+      }
+`).toMatchInlineSnapshot(`
+"
+# on start of line
+# should be aligned to start
+action \\"x\\" {
+  # should be indented
+  uses = \\"./ci\\" // should be at end
+}
+"
+`);
+  });
+
+  it("formats a file with unrecognized characters", () => {
+    expectFormatting(`
+# on start of line
+          # should be aligned to start
+              version =$
+`).toMatchInlineSnapshot(`
+"
+# on start of line
+# should be aligned to start
+version = $
+"
+`);
+  });
+});
+
+function expectFormatting(text: string): jest.Matchers<string> {
+  const compilation = new Compilation(text);
+  const result = FormattingService.format(compilation, "  ");
+
+  const secondCompilation = new Compilation(result);
+  const secondResult = FormattingService.format(secondCompilation, "  ");
+  expect(result).toBe(secondResult);
+
+  return expect(result);
+}