diff --git a/eslint.config.js b/eslint.config.js
index dedda10..5e5c704 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -14,7 +14,7 @@ export default [
       '@typescript-eslint/no-explicit-any': 'off',
       '@typescript-eslint/no-unused-vars': [
         'error',
-        {varsIgnorePattern: '^[A-Z_]'}
+        {varsIgnorePattern: '^[A-Z_]', argsIgnorePattern: '^_'}
       ]
     }
   }
diff --git a/src/analyze/attw.ts b/src/analyze/attw.ts
index adccb7e..78e0fdc 100644
--- a/src/analyze/attw.ts
+++ b/src/analyze/attw.ts
@@ -5,12 +5,13 @@ import {
 } from '@arethetypeswrong/core';
 import {groupProblemsByKind} from '@arethetypeswrong/core/utils';
 import {filterProblems, problemKindInfo} from '@arethetypeswrong/core/problems';
-import {ReportPluginResult} from '../types.js';
+import {ReportPluginResult, type Options} from '../types.js';
 import type {FileSystem} from '../file-system.js';
 import {TarballFileSystem} from '../tarball-file-system.js';
 
 export async function runAttw(
-  fileSystem: FileSystem
+  fileSystem: FileSystem,
+  _options?: Options
 ): Promise<ReportPluginResult> {
   const result: ReportPluginResult = {
     messages: []
diff --git a/src/analyze/dependencies.ts b/src/analyze/dependencies.ts
index 4e0810a..12bb722 100644
--- a/src/analyze/dependencies.ts
+++ b/src/analyze/dependencies.ts
@@ -4,7 +4,8 @@ import type {
   PackageJsonLike,
   ReportPluginResult,
   Message,
-  Stats
+  Stats,
+  Options
 } from '../types.js';
 import {FileSystem} from '../file-system.js';
 import {normalizePath} from '../utils/path.js';
@@ -147,7 +148,8 @@ async function parsePackageJson(
 
 // Keep the existing tarball analysis for backward compatibility
 export async function runDependencyAnalysis(
-  fileSystem: FileSystem
+  fileSystem: FileSystem,
+  _options?: Options
 ): Promise<ReportPluginResult> {
   const packageFiles = await fileSystem.listPackageFiles();
   const rootDir = await fileSystem.getRootDir();
diff --git a/src/analyze/publint.ts b/src/analyze/publint.ts
index ad80798..bba8fce 100644
--- a/src/analyze/publint.ts
+++ b/src/analyze/publint.ts
@@ -1,11 +1,12 @@
 import {publint} from 'publint';
 import {formatMessage} from 'publint/utils';
-import {ReportPluginResult} from '../types.js';
+import {ReportPluginResult, type Options} from '../types.js';
 import type {FileSystem} from '../file-system.js';
 import {TarballFileSystem} from '../tarball-file-system.js';
 
 export async function runPublint(
-  fileSystem: FileSystem
+  fileSystem: FileSystem,
+  _options?: Options
 ): Promise<ReportPluginResult> {
   const result: ReportPluginResult = {
     messages: []
diff --git a/src/analyze/replacements.ts b/src/analyze/replacements.ts
index 7d9b40f..7f0ee00 100644
--- a/src/analyze/replacements.ts
+++ b/src/analyze/replacements.ts
@@ -1,10 +1,17 @@
 import * as replacements from 'module-replacements';
+import type {ManifestModule, ModuleReplacement} from 'module-replacements';
 import {ReportPluginResult} from '../types.js';
 import type {FileSystem} from '../file-system.js';
 import {getPackageJson} from '../file-system-utils.js';
-import semverSatisfies from 'semver/functions/satisfies.js';
-import semverLessThan from 'semver/ranges/ltr.js';
-import {minVersion, validRange} from 'semver';
+import {resolve, dirname, basename} from 'node:path';
+import {
+  satisfies as semverSatisfies,
+  ltr as semverLessThan,
+  minVersion,
+  validRange
+} from 'semver';
+import {LocalFileSystem} from '../local-file-system.js';
+import type {Options} from '../types.js';
 
 /**
  * Generates a standard URL to the docs of a given rule
@@ -24,6 +31,42 @@ export function getMdnUrl(path: string): string {
   return `https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/${path}`;
 }
 
+async function loadCustomManifests(
+  manifestPaths?: string[]
+): Promise<ModuleReplacement[]> {
+  if (!manifestPaths || manifestPaths.length === 0) {
+    return [];
+  }
+
+  const customReplacements: ModuleReplacement[] = [];
+
+  for (const manifestPath of manifestPaths) {
+    try {
+      const absolutePath = resolve(manifestPath);
+      const manifestDir = dirname(absolutePath);
+      const manifestFileName = basename(absolutePath);
+      const localFileSystem = new LocalFileSystem(manifestDir);
+      const manifestContent = await localFileSystem.readFile(
+        `/${manifestFileName}`
+      );
+      const manifest: ManifestModule = JSON.parse(manifestContent);
+
+      if (
+        manifest.moduleReplacements &&
+        Array.isArray(manifest.moduleReplacements)
+      ) {
+        customReplacements.push(...manifest.moduleReplacements);
+      }
+    } catch (error) {
+      console.warn(
+        `Warning: Failed to load custom manifest from ${manifestPath}: ${error}`
+      );
+    }
+  }
+
+  return customReplacements;
+}
+
 function isNodeEngineCompatible(
   requiredNode: string,
   enginesNode: string
@@ -47,7 +90,8 @@ function isNodeEngineCompatible(
 }
 
 export async function runReplacements(
-  fileSystem: FileSystem
+  fileSystem: FileSystem,
+  options?: Options
 ): Promise<ReportPluginResult> {
   const result: ReportPluginResult = {
     messages: []
@@ -60,8 +104,18 @@ export async function runReplacements(
     return result;
   }
 
+  // Load custom manifests
+  const customReplacements = await loadCustomManifests(options?.manifest);
+
+  // Combine custom and built-in replacements
+  const allReplacements = [
+    ...customReplacements,
+    ...replacements.all.moduleReplacements
+  ];
+
   for (const name of Object.keys(packageJson.dependencies)) {
-    const replacement = replacements.all.moduleReplacements.find(
+    // Find replacement (custom replacements take precedence due to order)
+    const replacement = allReplacements.find(
       (replacement) => replacement.moduleName === name
     );
 
@@ -69,6 +123,7 @@ export async function runReplacements(
       continue;
     }
 
+    // Handle each replacement type using the same logic for both custom and built-in
     if (replacement.type === 'none') {
       result.messages.push({
         severity: 'warning',
@@ -101,17 +156,21 @@ export async function runReplacements(
         replacement.nodeVersion && !enginesNode
           ? ` Required Node >= ${replacement.nodeVersion}.`
           : '';
+      const message = `Module "${name}" can be replaced with native functionality. Use "${replacement.replacement}" instead.${requires}`;
+      const fullMessage = `${message} You can read more at ${mdnPath}.`;
       result.messages.push({
         severity: 'warning',
         score: 0,
-        message: `Module "${name}" can be replaced with native functionality. Use "${replacement.replacement}" instead. You can read more at ${mdnPath}.${requires}`
+        message: fullMessage
       });
     } else if (replacement.type === 'documented') {
       const docUrl = getDocsUrl(replacement.docPath);
+      const message = `Module "${name}" can be replaced with a more performant alternative.`;
+      const fullMessage = `${message} See the list of available alternatives at ${docUrl}.`;
       result.messages.push({
         severity: 'warning',
         score: 0,
-        message: `Module "${name}" can be replaced with a more performant alternative. See the list of available alternatives at ${docUrl}.`
+        message: fullMessage
       });
     }
   }
diff --git a/src/analyze/report.ts b/src/analyze/report.ts
index b7f839f..2c5d0c6 100644
--- a/src/analyze/report.ts
+++ b/src/analyze/report.ts
@@ -65,7 +65,7 @@ export async function report(options: Options) {
   }
 
   for (const plugin of plugins) {
-    const result = await plugin(fileSystem);
+    const result = await plugin(fileSystem, options);
 
     for (const message of result.messages) {
       messages.push(message);
diff --git a/src/commands/analyze.meta.ts b/src/commands/analyze.meta.ts
index e7bfd03..4071898 100644
--- a/src/commands/analyze.meta.ts
+++ b/src/commands/analyze.meta.ts
@@ -22,6 +22,12 @@ export const meta = {
       choices: ['debug', 'info', 'warn', 'error'],
       default: 'info',
       description: 'Set the log level (debug | info | warn | error)'
+    },
+    manifest: {
+      type: 'string',
+      array: true,
+      description:
+        'Path(s) to custom manifest file(s) for module replacements analysis'
     }
   }
 } as const;
diff --git a/src/commands/analyze.ts b/src/commands/analyze.ts
index ceb7f03..717b1c1 100644
--- a/src/commands/analyze.ts
+++ b/src/commands/analyze.ts
@@ -77,8 +77,22 @@ export async function run(ctx: CommandContext<typeof meta.args>) {
     }
   }
 
-  // Analyze
-  const {stats, messages} = await report({root, pack});
+  // Then analyze the tarball
+  const rawCustomManifests = ctx.values['manifest'];
+
+  // NOTE: Gunshi quirk - array arguments are sometimes returned as single strings
+  // when only one value is provided, so we need to handle both cases
+  const customManifests = Array.isArray(rawCustomManifests)
+    ? rawCustomManifests
+    : rawCustomManifests
+      ? [rawCustomManifests]
+      : [];
+
+  const {stats, messages} = await report({
+    root,
+    pack,
+    manifest: customManifests
+  });
 
   prompts.log.info('Summary');
 
diff --git a/src/test/__snapshots__/custom-manifests.test.ts.snap b/src/test/__snapshots__/custom-manifests.test.ts.snap
new file mode 100644
index 0000000..2ebaff8
--- /dev/null
+++ b/src/test/__snapshots__/custom-manifests.test.ts.snap
@@ -0,0 +1,106 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`Custom Manifests > should handle invalid manifest files gracefully 1`] = `[]`;
+
+exports[`Custom Manifests > should load and use custom manifest files 1`] = `
+[
+  {
+    "message": "Module "@e18e/fake-0" can be replaced. Use picocolors, kleur, or native console styling.",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-1" can be replaced. Use native JavaScript methods or specific lodash functions.",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-2" can be replaced with native functionality. Use "Intl.DateTimeFormat or Date methods" instead. Required Node >= 12.0.0. You can read more at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat.",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-3" can be replaced with a more performant alternative. See the list of available alternatives at https://github.com/es-tooling/eslint-plugin-depend/blob/main/docs/rules/request-alternatives.md.",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-4" can be removed, and native functionality used instead",
+    "score": 0,
+    "severity": "warning",
+  },
+]
+`;
+
+exports[`Custom Manifests > should load multiple manifest files 1`] = `
+[
+  {
+    "message": "Module "@e18e/fake-0" can be replaced. Use picocolors, kleur, or native console styling.",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-1" can be replaced. Use native JavaScript methods or specific lodash functions.",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-2" can be replaced with native functionality. Use "Intl.DateTimeFormat or Date methods" instead. Required Node >= 12.0.0. You can read more at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat.",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-3" can be replaced with a more performant alternative. See the list of available alternatives at https://github.com/es-tooling/eslint-plugin-depend/blob/main/docs/rules/request-alternatives.md.",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-4" can be removed, and native functionality used instead",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-5" can be replaced. Use Fastify, Koa, or native Node.js http module.",
+    "score": 0,
+    "severity": "warning",
+  },
+  {
+    "message": "Module "@e18e/fake-6" can be removed, and native functionality used instead",
+    "score": 0,
+    "severity": "warning",
+  },
+]
+`;
+
+exports[`Custom Manifests > should prioritize custom replacements over built-in ones 1`] = `
+{
+  "withCustom": [
+    {
+      "message": "Module "@e18e/fake-0" can be replaced. Use picocolors, kleur, or native console styling.",
+      "score": 0,
+      "severity": "warning",
+    },
+    {
+      "message": "Module "@e18e/fake-1" can be replaced. Use native JavaScript methods or specific lodash functions.",
+      "score": 0,
+      "severity": "warning",
+    },
+    {
+      "message": "Module "@e18e/fake-2" can be replaced with native functionality. Use "Intl.DateTimeFormat or Date methods" instead. Required Node >= 12.0.0. You can read more at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat.",
+      "score": 0,
+      "severity": "warning",
+    },
+    {
+      "message": "Module "@e18e/fake-3" can be replaced with a more performant alternative. See the list of available alternatives at https://github.com/es-tooling/eslint-plugin-depend/blob/main/docs/rules/request-alternatives.md.",
+      "score": 0,
+      "severity": "warning",
+    },
+    {
+      "message": "Module "@e18e/fake-4" can be removed, and native functionality used instead",
+      "score": 0,
+      "severity": "warning",
+    },
+  ],
+  "withoutCustom": [],
+}
+`;
diff --git a/src/test/custom-manifests.test.ts b/src/test/custom-manifests.test.ts
new file mode 100644
index 0000000..03808b8
--- /dev/null
+++ b/src/test/custom-manifests.test.ts
@@ -0,0 +1,75 @@
+import {describe, it, expect} from 'vitest';
+import {runReplacements} from '../analyze/replacements.js';
+import {LocalFileSystem} from '../local-file-system.js';
+import {join} from 'node:path';
+import {fileURLToPath} from 'node:url';
+import {dirname} from 'node:path';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+describe('Custom Manifests', () => {
+  it('should load and use custom manifest files', async () => {
+    const testDir = join(__dirname, '../../test/fixtures/fake-modules');
+    const fileSystem = new LocalFileSystem(testDir);
+    const customManifestPath = join(
+      __dirname,
+      '../../test/fixtures/custom-manifest.json'
+    );
+
+    const result = await runReplacements(fileSystem, {
+      manifest: [customManifestPath]
+    });
+
+    expect(result.messages).toMatchSnapshot();
+  });
+
+  it('should handle invalid manifest files gracefully', async () => {
+    const testDir = join(__dirname, '../../test/fixtures/fake-modules');
+    const fileSystem = new LocalFileSystem(testDir);
+    const invalidManifestPath = 'non-existent-file.json';
+
+    const result = await runReplacements(fileSystem, {
+      manifest: [invalidManifestPath]
+    });
+
+    expect(result.messages).toMatchSnapshot();
+  });
+
+  it('should prioritize custom replacements over built-in ones', async () => {
+    const testDir = join(__dirname, '../../test/fixtures/fake-modules');
+    const fileSystem = new LocalFileSystem(testDir);
+    const customManifestPath = join(
+      __dirname,
+      '../../test/fixtures/custom-manifest.json'
+    );
+
+    const resultWithCustom = await runReplacements(fileSystem, {
+      manifest: [customManifestPath]
+    });
+    const resultWithoutCustom = await runReplacements(fileSystem);
+
+    expect({
+      withCustom: resultWithCustom.messages,
+      withoutCustom: resultWithoutCustom.messages
+    }).toMatchSnapshot();
+  });
+
+  it('should load multiple manifest files', async () => {
+    const testDir = join(__dirname, '../../test/fixtures/fake-modules');
+    const fileSystem = new LocalFileSystem(testDir);
+    const manifest1Path = join(
+      __dirname,
+      '../../test/fixtures/custom-manifest.json'
+    );
+    const manifest2Path = join(
+      __dirname,
+      '../../test/fixtures/custom-manifest-2.json'
+    );
+
+    const result = await runReplacements(fileSystem, {
+      manifest: [manifest1Path, manifest2Path]
+    });
+
+    expect(result.messages).toMatchSnapshot();
+  });
+});
diff --git a/src/types.ts b/src/types.ts
index 8244e26..3e5ac8e 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -18,6 +18,7 @@ export type PackType =
 export interface Options {
   root?: string;
   pack?: PackType;
+  manifest?: string[];
 }
 
 export interface StatLike<T> {
@@ -72,5 +73,6 @@ export interface ReportPluginResult {
 }
 
 export type ReportPlugin = (
-  fileSystem: FileSystem
+  fileSystem: FileSystem,
+  options?: Options
 ) => Promise<ReportPluginResult>;
diff --git a/test/fixtures/custom-manifest-2.json b/test/fixtures/custom-manifest-2.json
new file mode 100644
index 0000000..a979190
--- /dev/null
+++ b/test/fixtures/custom-manifest-2.json
@@ -0,0 +1,14 @@
+{
+  "moduleReplacements": [
+    {
+      "moduleName": "@e18e/fake-5",
+      "type": "simple",
+      "replacement": "Use Fastify, Koa, or native Node.js http module"
+    },
+    {
+      "moduleName": "@e18e/fake-6",
+      "type": "none",
+      "replacement": "Use native JSON.parse or built-in middleware"
+    }
+  ]
+}
diff --git a/test/fixtures/custom-manifest.json b/test/fixtures/custom-manifest.json
new file mode 100644
index 0000000..6170e1a
--- /dev/null
+++ b/test/fixtures/custom-manifest.json
@@ -0,0 +1,32 @@
+{
+  "moduleReplacements": [
+    {
+      "moduleName": "@e18e/fake-0",
+      "type": "simple",
+      "replacement": "Use picocolors, kleur, or native console styling"
+    },
+    {
+      "moduleName": "@e18e/fake-1",
+      "type": "simple",
+      "replacement": "Use native JavaScript methods or specific lodash functions"
+    },
+    {
+      "moduleName": "@e18e/fake-2",
+      "type": "native",
+      "replacement": "Intl.DateTimeFormat or Date methods",
+      "mdnPath": "Global_Objects/Intl/DateTimeFormat",
+      "nodeVersion": "12.0.0"
+    },
+    {
+      "moduleName": "@e18e/fake-3",
+      "type": "documented",
+      "replacement": "node-fetch, axios, or native fetch",
+      "docPath": "request-alternatives"
+    },
+    {
+      "moduleName": "@e18e/fake-4",
+      "type": "none",
+      "replacement": "Use native Promise methods"
+    }
+  ]
+}
diff --git a/test/fixtures/fake-modules/package.json b/test/fixtures/fake-modules/package.json
new file mode 100644
index 0000000..9e757cf
--- /dev/null
+++ b/test/fixtures/fake-modules/package.json
@@ -0,0 +1,13 @@
+{
+  "name": "fake-modules-test",
+  "version": "1.0.0",
+  "dependencies": {
+    "@e18e/fake-0": "^1.0.0",
+    "@e18e/fake-1": "^2.0.0",
+    "@e18e/fake-2": "^3.0.0",
+    "@e18e/fake-3": "^4.0.0",
+    "@e18e/fake-4": "^5.0.0",
+    "@e18e/fake-5": "^6.0.0",
+    "@e18e/fake-6": "^7.0.0"
+  }
+}