diff --git a/.vscode/settings.json b/.vscode/settings.json
index aa1c94e..ebd5461 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,4 +1,15 @@
 {
   "deno.enable": true,
-  "deno.unstable": true
+  "deno.unstable": true,
+  "editor.formatOnSave": true,
+  "editor.defaultFormatter": "denoland.vscode-deno",
+  "[javascript]": {
+    "editor.defaultFormatter": "denoland.vscode-deno"
+  },
+  "[typescript]": {
+    "editor.defaultFormatter": "denoland.vscode-deno"
+  },
+  "[json]": {
+    "editor.defaultFormatter": "denoland.vscode-deno"
+  }
 }
diff --git a/src/commands/generate.ts b/src/commands/generate.ts
index c8e2009..94bc941 100644
--- a/src/commands/generate.ts
+++ b/src/commands/generate.ts
@@ -42,6 +42,7 @@ export async function fromConfig(configContents: string) {
     .split("---")
     .map((v) => v.trim())
     .map((v) => yaml.parse(v) as Configuration);
+
   const outputs: Output[] = [];
   for (const config of configs) {
     const o = await process(config);
diff --git a/src/config.ts b/src/config.ts
index 3d5d17f..39566a6 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -5,7 +5,8 @@ export type Config = { [key: string]: unknown };
 export interface Configuration {
   spec: string;
   config?: Config;
-  generates: Record<string, Target>;
+  plugins?: string[];
+  generates?: Record<string, Target>;
 }
 
 export interface Target {
diff --git a/src/generate.ts b/src/generate.ts
index 9ce2319..602aa61 100644
--- a/src/generate.ts
+++ b/src/generate.ts
@@ -5,13 +5,15 @@ import * as path from "https://deno.land/std@0.167.0/path/mod.ts";
 import * as streams from "https://deno.land/std@0.167.0/streams/read_all.ts";
 
 import { Config, Configuration, Output } from "./config.ts";
-import { existsSync } from "./utils.ts";
+import { existsSync, makeRelativeUrl } from "./utils.ts";
 
-async function processConfig(config: Configuration): Promise<Output[]> {
+export async function processConfig(config: Configuration): Promise<Output[]> {
   const apexSource = await Deno.readTextFile(config.spec);
   // TODO: implement resolver callback
   const doc = apex.parse(apexSource);
 
+  config = await processPlugin(doc, config);
+
   const output: Output[] = [];
   for (const file in config.generates) {
     const generatorConfig = config.generates[file];
@@ -21,11 +23,7 @@ async function processConfig(config: Configuration): Promise<Output[]> {
       //log.info(`Skipping ${file}`);
       continue;
     }
-
-    const url = generatorConfig.module.startsWith(".") ||
-        generatorConfig.module.startsWith("/")
-      ? new URL("file:///" + path.join(Deno.cwd(), generatorConfig.module))
-      : new URL(generatorConfig.module);
+    const url = makeRelativeUrl(generatorConfig.module);
 
     const visitorConfig: Config = {};
     if (config.config) {
@@ -68,6 +66,22 @@ async function processConfig(config: Configuration): Promise<Output[]> {
   return output;
 }
 
+export async function processPlugin(
+  doc: apex.ast.Document,
+  config: Configuration,
+): Promise<Configuration> {
+  for (const file of config.plugins || []) {
+    const url = makeRelativeUrl(file);
+
+    log.debug(`Generating configuration with plugin from ${url}`);
+
+    const plugin = await import(url.toString());
+    config = plugin.default(doc, config);
+  }
+
+  return config;
+}
+
 // Detect piped input
 if (!Deno.isatty(Deno.stdin.rid) && import.meta.main) {
   const stdinContent = await streams.readAll(Deno.stdin);
diff --git a/src/process.ts b/src/process.ts
index 33a683a..9bb863d 100644
--- a/src/process.ts
+++ b/src/process.ts
@@ -6,6 +6,8 @@ import { Configuration, Output } from "./config.ts";
 import { cliFormatters, sourceFormatters } from "./formatters.ts";
 
 export async function process(config: Configuration): Promise<Output[]> {
+  log.debug(`Configuration is: ${JSON.stringify(config, null, 2)}`);
+
   // Run the generation process with restricted permissions.
   const href = new URL("./generate.ts", import.meta.url).href;
   const p = await Deno.run({
@@ -38,6 +40,7 @@ export async function process(config: Configuration): Promise<Output[]> {
   }
 
   const output = new TextDecoder().decode(rawOutput);
+  log.debug(`Generator output: ${output}`);
   return JSON.parse(output) as Output[];
 }
 
@@ -68,7 +71,10 @@ export async function writeOutput(generated: Output): Promise<void> {
   // Execute additional tooling via "runAfter".
   if (generated.runAfter) {
     generated.runAfter.forEach(async (cmdConfig) => {
-      const joined = cmdConfig.command.trim().split("\n").map((v) => v.trim())
+      const joined = cmdConfig.command
+        .trim()
+        .split("\n")
+        .map((v) => v.trim())
         .join(" ");
       const args = joined.split(/\s+/);
       const cmd = args.shift()!;
diff --git a/src/utils.ts b/src/utils.ts
index e22c74a..8c7ca11 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -84,3 +84,11 @@ export async function mkdirAll(path: string, mode: number) {
     }
   }
 }
+
+export function makeRelativeUrl(file: string): URL {
+  return file.startsWith(".")
+    ? new URL("file:///" + path.join(Deno.cwd(), file))
+    : file.startsWith("/")
+    ? new URL("file:///" + file)
+    : new URL(file);
+}
diff --git a/test/config.test.ts b/test/config.test.ts
index da661ab..71bc5a0 100644
--- a/test/config.test.ts
+++ b/test/config.test.ts
@@ -4,7 +4,6 @@ import * as path from "https://deno.land/std@0.167.0/path/mod.ts";
 
 const __dirname = new URL(".", import.meta.url).pathname;
 
-// Compact form: name and function
 Deno.test(
   "process",
   { permissions: { read: true, net: true, run: true } },
@@ -20,10 +19,12 @@ Deno.test(
     });
 
     const fixture = await Deno.readTextFile(path.join(__dirname, "fixture.rs"));
-    assertEquals(generated, [{
-      file: "file.rs",
-      source: fixture,
-      executable: false,
-    }]);
-  },
+    assertEquals(generated, [
+      {
+        file: "file.rs",
+        source: fixture,
+        executable: false,
+      },
+    ]);
+  }
 );
diff --git a/test/plugin.test.ts b/test/plugin.test.ts
new file mode 100644
index 0000000..d30c93a
--- /dev/null
+++ b/test/plugin.test.ts
@@ -0,0 +1,69 @@
+import * as apex from "https://deno.land/x/apex_core@v0.1.1/mod.ts";
+import { assertEquals } from "https://deno.land/std@0.167.0/testing/asserts.ts";
+import { processPlugin, processConfig } from "../src/generate.ts";
+import * as path from "https://deno.land/std@0.167.0/path/mod.ts";
+
+const __dirname = new URL(".", import.meta.url).pathname;
+const spec = path.join(__dirname, "test.axdl");
+const plugin = path.join(__dirname, "test-plugin.ts");
+const generator = path.join(__dirname, "test-generator.ts");
+
+Deno.test(
+  "plugin",
+  { permissions: { read: true, net: true, run: true } },
+  async () => {
+    const apexSource = await Deno.readTextFile(spec);
+    const doc = apex.parse(apexSource);
+    const config = await processPlugin(doc, {
+      spec,
+      plugins: [plugin],
+    });
+
+    assertEquals(config.generates, { "Test.0.file": { module: generator } });
+  }
+);
+
+Deno.test(
+  "plugin",
+  { permissions: { read: true, net: true, run: true } },
+  async () => {
+    const apexSource = await Deno.readTextFile(spec);
+    const doc = apex.parse(apexSource);
+    const config = await processPlugin(doc, {
+      spec,
+      plugins: [plugin, plugin],
+    });
+
+    assertEquals(config.generates, {
+      "Test.0.file": { module: generator },
+      "Test.1.file": { module: generator },
+    });
+  }
+);
+
+Deno.test(
+  "generate",
+  { permissions: { read: true, net: true, run: true } },
+  async () => {
+    const apexSource = await Deno.readTextFile(spec);
+    const output = await processConfig({
+      spec,
+      plugins: [plugin, plugin],
+    });
+
+    assertEquals(output, [
+      {
+        file: "Test.0.file",
+        source: "startend",
+        executable: false,
+        runAfter: undefined,
+      },
+      {
+        file: "Test.1.file",
+        source: "startend",
+        executable: false,
+        runAfter: undefined,
+      },
+    ]);
+  }
+);
diff --git a/test/test-generator.ts b/test/test-generator.ts
new file mode 100644
index 0000000..1fa1f50
--- /dev/null
+++ b/test/test-generator.ts
@@ -0,0 +1,15 @@
+import * as model from "https://deno.land/x/apex_core@v0.1.0/model/mod.ts";
+
+type Context = model.Context;
+
+export default class DefaultVisitor extends model.BaseVisitor {
+  visitContextBefore(context: Context): void {
+    super.visitContextBefore(context);
+    this.write("start");
+  }
+
+  visitContextAfter(context: Context): void {
+    super.visitContextAfter(context);
+    this.write("end");
+  }
+}
diff --git a/test/test-plugin.ts b/test/test-plugin.ts
new file mode 100644
index 0000000..8ade21b
--- /dev/null
+++ b/test/test-plugin.ts
@@ -0,0 +1,23 @@
+import { Configuration } from "../src/config.ts";
+import * as apex from "https://deno.land/x/apex_core@v0.1.0/mod.ts";
+import * as path from "https://deno.land/std@0.167.0/path/mod.ts";
+
+const __dirname = new URL(".", import.meta.url).pathname;
+const generator = path.join(__dirname, "test-generator.ts");
+
+export default function (
+  doc: apex.ast.Document,
+  config: Configuration
+): Configuration {
+  config.generates ||= {};
+  const interfaces = doc.definitions.filter(
+    (def) => def.getKind() === apex.ast.Kind.InterfaceDefinition
+  ) as apex.ast.InterfaceDefinition[];
+  const num = Object.keys(config.generates).length;
+  for (const iface of interfaces) {
+    config.generates[`${iface.name.value}.${num}.file`] = {
+      module: generator,
+    };
+  }
+  return config;
+}