diff --git a/jest.integration.config.cjs b/jest.integration.config.cjs
index e6d178d..0ce1a64 100644
--- a/jest.integration.config.cjs
+++ b/jest.integration.config.cjs
@@ -1,3 +1,10 @@
+const { randomBytes } = require("crypto");
+const path = require("path");
+const os = require("os");
+
+const ROOT_TEST_BRANCH_PREFIX = `test-${randomBytes(4).toString("hex")}`;
+const ROOT_TEMP_DIRECTORY = path.join(os.tmpdir(), ROOT_TEST_BRANCH_PREFIX);
+
 module.exports = {
   preset: "ts-jest",
   testEnvironment: "node",
@@ -17,4 +24,9 @@ module.exports = {
     "^(.+).js$": "$1",
   },
   testMatch: ["<rootDir>/src/test/integration/**/*.test.ts"],
+  globals: {
+    ROOT_TEST_BRANCH_PREFIX,
+    ROOT_TEMP_DIRECTORY,
+  },
+  globalTeardown: "<rootDir>/src/test/integration/jest.globalTeardown.ts",
 };
diff --git a/package.json b/package.json
index c829eb1..e08ae85 100644
--- a/package.json
+++ b/package.json
@@ -26,13 +26,11 @@
     }
   },
   "scripts": {
-    "build": "pnpm codegen:github && tsc --noEmit && tsup",
+    "build": "rm -rf dist && pnpm codegen:github && tsc --noEmit && tsup",
     "codegen:github": "graphql-codegen --config src/github/codegen.ts",
     "format:check": "prettier --check \"**/*.{ts,tsx,md}\"",
     "format:fix": "prettier --write \"**/*.{ts,tsx,md}\"",
     "lint": "eslint . --max-warnings 0",
-    "test": "jest",
-    "test:watch": "jest --watch",
     "test:integration": "jest --config jest.integration.config.cjs"
   },
   "devDependencies": {
diff --git a/src/core.ts b/src/core.ts
new file mode 100644
index 0000000..81a352b
--- /dev/null
+++ b/src/core.ts
@@ -0,0 +1,100 @@
+import type {
+  CommitMessage,
+  FileChanges,
+} from "./github/graphql/generated/types.js";
+import {
+  createCommitOnBranchQuery,
+  createRefMutation,
+  getRepositoryMetadata,
+  GitHubClient,
+} from "./github/graphql/queries.js";
+import type { CreateCommitOnBranchMutationVariables } from "./github/graphql/generated/operations.js";
+import type { Logger } from "./logging.js";
+
+export type CommitFilesResult = {
+  refId: string | null;
+};
+
+export type CommitFilesFromBase64Args = {
+  octokit: GitHubClient;
+  owner: string;
+  repository: string;
+  branch: string;
+  /**
+   * The current commit that the target branch is at
+   */
+  baseBranch: string;
+  /**
+   * The commit message
+   */
+  message: CommitMessage;
+  fileChanges: FileChanges;
+  log?: Logger;
+};
+
+export const commitFilesFromBase64 = async ({
+  octokit,
+  owner,
+  repository,
+  branch,
+  baseBranch,
+  message,
+  fileChanges,
+  log,
+}: CommitFilesFromBase64Args): Promise<CommitFilesResult> => {
+  const repositoryNameWithOwner = `${owner}/${repository}`;
+  const baseRef = `refs/heads/${baseBranch}`;
+
+  log?.debug(`Getting repo info ${repositoryNameWithOwner}`);
+  const info = await getRepositoryMetadata(octokit, {
+    owner,
+    name: repository,
+    ref: baseRef,
+  });
+  log?.debug(`Repo info: ${JSON.stringify(info, null, 2)}`);
+
+  if (!info) {
+    throw new Error(`Repository ${repositoryNameWithOwner} not found`);
+  }
+
+  const oid = info.ref?.target?.oid;
+
+  if (!info) {
+    throw new Error(`Ref ${baseRef} not found`);
+  }
+
+  log?.debug(`Creating branch ${branch} from commit ${oid}}`);
+  const refId = await createRefMutation(octokit, {
+    input: {
+      repositoryId: info.id,
+      name: `refs/heads/${branch}`,
+      oid,
+    },
+  });
+
+  log?.debug(`Created branch with refId ${JSON.stringify(refId, null, 2)}`);
+
+  const refIdStr = refId.createRef?.ref?.id;
+
+  if (!refIdStr) {
+    throw new Error(`Failed to create branch ${branch}`);
+  }
+
+  await log?.debug(`Creating commit on branch ${branch}`);
+  const createCommitMutation: CreateCommitOnBranchMutationVariables = {
+    input: {
+      branch: {
+        id: refIdStr,
+      },
+      expectedHeadOid: oid,
+      message,
+      fileChanges,
+    },
+  };
+  log?.debug(JSON.stringify(createCommitMutation, null, 2));
+
+  const result = await createCommitOnBranchQuery(octokit, createCommitMutation);
+  return {
+    refId: result.createCommitOnBranch?.ref?.id ?? null,
+  };
+};
diff --git a/src/fs.ts b/src/fs.ts
index 522179f..1aa136b 100644
--- a/src/fs.ts
+++ b/src/fs.ts
@@ -1,126 +1,43 @@
 import { promises as fs } from "fs";
 import * as path from "path";
-import type {
-  CommitMessage,
-  FileAddition,
-  FileDeletion,
-} from "./github/graphql/generated/types";
-import {
-  createCommitOnBranchQuery,
-  createRefMutation,
-  getRepositoryMetadata,
-  GitHubClient,
-} from "./github/graphql/queries";
-import type { CreateCommitOnBranchMutationVariables } from "./github/graphql/generated/operations";
-import type { Logger } from "./logging";
-
-export const commitFilesFromDirectory = async (args: {
-  octokit: GitHubClient;
+import type { FileAddition } from "./github/graphql/generated/types.js";
+import { CommitFilesFromBase64Args, CommitFilesResult } from "./core.js";
+import { commitFilesFromBuffers } from "./node.js";
+
+export type CommitFilesFromDirectoryArgs = Omit<
+  CommitFilesFromBase64Args,
+  "fileChanges"
+> & {
   /**
-   * The root of the github repository.
+   * The directory to consider the root of the repository when calculating
+   * file paths
    */
   workingDirectory?: string;
-  owner: string;
-  repository: string;
-  branch: string;
-  /**
-   * The current commit that the target branch is at
-   */
-  baseBranch: string;
-  /**
-   * The commit message
-   */
-  message: CommitMessage;
   fileChanges: {
-    /**
-     * File paths (relative to the repository root)
-     */
     additions?: string[];
     deletions?: string[];
   };
-  log?: Logger;
-}) => {
-  const {
-    octokit,
-    workingDirectory = process.cwd(),
-    owner,
-    repository,
-    branch,
-    baseBranch,
-    message,
-    fileChanges,
-    log,
-  } = args;
-  const repositoryNameWithOwner = `${owner}/${repository}`;
-  const baseRef = `refs/heads/${baseBranch}`;
+};
 
+export const commitFilesFromDirectory = async ({
+  workingDirectory = process.cwd(),
+  fileChanges,
+  ...otherArgs
+}: CommitFilesFromDirectoryArgs): Promise<CommitFilesResult> => {
   const additions: FileAddition[] = await Promise.all(
     (fileChanges.additions || []).map(async (p) => {
-      const fileContents = await fs.readFile(path.join(workingDirectory, p));
-      const base64Contents = Buffer.from(fileContents).toString("base64");
       return {
         path: p,
-        contents: base64Contents,
+        contents: await fs.readFile(path.join(workingDirectory, p)),
       };
     }),
   );
 
-  const deletions: FileDeletion[] =
-    fileChanges.deletions?.map((p) => ({
-      path: p,
-    })) ?? [];
-
-  log?.debug(`Getting repo info ${repositoryNameWithOwner}`);
-  const info = await getRepositoryMetadata(octokit, {
-    owner: args.owner,
-    name: args.repository,
-    ref: baseRef,
-  });
-  log?.debug(`Repo info: ${JSON.stringify(info, null, 2)}`);
-
-  if (!info) {
-    throw new Error(`Repository ${repositoryNameWithOwner} not found`);
-  }
-
-  const oid = info.ref?.target?.oid;
-
-  if (!info) {
-    throw new Error(`Ref ${baseRef} not found`);
-  }
-
-  log?.debug(`Creating branch ${branch} from commit ${oid}}`);
-  const refId = await createRefMutation(octokit, {
-    input: {
-      repositoryId: info.id,
-      name: `refs/heads/${branch}`,
-      oid,
+  return commitFilesFromBuffers({
+    ...otherArgs,
+    fileChanges: {
+      additions,
+      deletions: fileChanges.deletions,
     },
   });
-
-  log?.debug(`Created branch with refId ${JSON.stringify(refId, null, 2)}`);
-
-  const refIdStr = refId.createRef?.ref?.id;
-
-  if (!refIdStr) {
-    throw new Error(`Failed to create branch ${branch}`);
-  }
-
-  await log?.debug(`Creating commit on branch ${args.branch}`);
-  const createCommitMutation: CreateCommitOnBranchMutationVariables = {
-    input: {
-      branch: {
-        id: refIdStr,
-      },
-      expectedHeadOid: oid,
-      message,
-      fileChanges: {
-        additions,
-        deletions,
-      },
-    },
-  };
-  log?.debug(JSON.stringify(createCommitMutation, null, 2));
-
-  const result = await createCommitOnBranchQuery(octokit, createCommitMutation);
-  return result.createCommitOnBranch?.ref?.id ?? null;
 };
diff --git a/src/github/graphql/queries.ts b/src/github/graphql/queries.ts
index 50783e5..04caea3 100644
--- a/src/github/graphql/queries.ts
+++ b/src/github/graphql/queries.ts
@@ -1,6 +1,6 @@
-import type { GitHub } from "@actions/github/lib/utils";
-
-export type GitHubClient = InstanceType<typeof GitHub>;
+export type GitHubClient = {
+  graphql: <T>(query: string, variables: any) => Promise<T>;
+};
 
 import type {
   CreateCommitOnBranchMutation,
@@ -11,7 +11,7 @@ import type {
   DeleteRefMutationVariables,
   GetRepositoryMetadataQuery,
   GetRepositoryMetadataQueryVariables,
-} from "./generated/operations";
+} from "./generated/operations.js";
 
 const GET_REPOSITORY_METADATA = /* GraphQL */ `
   query getRepositoryMetadata($owner: String!, $name: String!, $ref: String!) {
diff --git a/src/index.ts b/src/index.ts
index 247698c..f0f0c05 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,2 +1,2 @@
-export * as queries from "./github/graphql/queries";
-export { commitFilesFromDirectory } from "./fs";
+export * as queries from "./github/graphql/queries.js";
+export { commitFilesFromDirectory } from "./fs.js";
diff --git a/src/node.ts b/src/node.ts
new file mode 100644
index 0000000..fb07095
--- /dev/null
+++ b/src/node.ts
@@ -0,0 +1,34 @@
+import {
+  commitFilesFromBase64,
+  CommitFilesFromBase64Args,
+  CommitFilesResult,
+} from "./core.js";
+
+export type CommitFilesFromBuffersArgs = Omit<
+  CommitFilesFromBase64Args,
+  "fileChanges"
+> & {
+  fileChanges: {
+    additions?: Array<{
+      path: string;
+      contents: Buffer;
+    }>;
+    deletions?: string[];
+  };
+};
+
+export const commitFilesFromBuffers = async ({
+  fileChanges,
+  ...otherArgs
+}: CommitFilesFromBuffersArgs): Promise<CommitFilesResult> => {
+  return commitFilesFromBase64({
+    ...otherArgs,
+    fileChanges: {
+      additions: fileChanges.additions?.map(({ path, contents }) => ({
+        path,
+        contents: contents.toString("base64"),
+      })),
+      deletions: fileChanges.deletions?.map((path) => ({ path })),
+    },
+  });
+};
diff --git a/src/test/integration/env.ts b/src/test/integration/env.ts
new file mode 100644
index 0000000..8074d44
--- /dev/null
+++ b/src/test/integration/env.ts
@@ -0,0 +1,37 @@
+import { pino } from "pino";
+import { configDotenv } from "dotenv";
+
+declare namespace global {
+  const ROOT_TEST_BRANCH_PREFIX: string;
+  const ROOT_TEMP_DIRECTORY: string;
+}
+
+export const ROOT_TEST_BRANCH_PREFIX = global.ROOT_TEST_BRANCH_PREFIX;
+export const ROOT_TEMP_DIRECTORY = global.ROOT_TEMP_DIRECTORY;
+
+configDotenv();
+
+const GITHUB_TOKEN = process.env.GITHUB_TOKEN;
+if (!GITHUB_TOKEN) {
+  throw new Error("GITHUB_TOKEN must be set");
+}
+
+const GITHUB_REPOSITORY = process.env.GITHUB_REPOSITORY;
+
+const [owner, repository] = GITHUB_REPOSITORY?.split("/") || [];
+if (!owner || !repository) {
+  throw new Error("GITHUB_REPOSITORY must be set");
+}
+
+export const ENV = {
+  GITHUB_TOKEN,
+};
+
+export const REPO = { owner, repository };
+
+export const log = pino({
+  level: process.env.RUNNER_DEBUG === "1" ? "debug" : "info",
+  transport: {
+    target: "pino-pretty",
+  },
+});
diff --git a/src/test/integration/fs.test.ts b/src/test/integration/fs.test.ts
index f62ea14..386392c 100644
--- a/src/test/integration/fs.test.ts
+++ b/src/test/integration/fs.test.ts
@@ -1,60 +1,34 @@
-/**
- * This file includes tests that will be run in CI.
- */
-import * as os from "os";
 import * as path from "path";
 import { promises as fs } from "fs";
-import { getOctokit } from "@actions/github/lib/github";
-import pino from "pino";
-import { configDotenv } from "dotenv";
+import { getOctokit } from "@actions/github/lib/github.js";
 
-import { commitFilesFromDirectory } from "../../fs";
-import { randomBytes } from "crypto";
+import { commitFilesFromDirectory } from "../../fs.js";
 import {
-  deleteRefMutation,
-  getRepositoryMetadata,
-} from "../../github/graphql/queries";
+  ENV,
+  REPO,
+  ROOT_TEMP_DIRECTORY,
+  ROOT_TEST_BRANCH_PREFIX,
+  log,
+} from "./env.js";
+import { deleteBranches } from "./util.js";
 
-configDotenv();
-
-const GITHUB_TOKEN = process.env.GITHUB_TOKEN;
-if (!GITHUB_TOKEN) {
-  throw new Error("GITHUB_TOKEN must be set");
-}
-
-const GITHUB_REPOSITORY = process.env.GITHUB_REPOSITORY;
-
-const [owner, repository] = GITHUB_REPOSITORY?.split("/") || [];
-if (!owner || !repository) {
-  throw new Error("GITHUB_REPOSITORY must be set");
-}
-
-const log = pino({
-  level: process.env.RUNNER_DEBUG === "1" ? "debug" : "info",
-  transport: {
-    target: "pino-pretty",
-  },
-});
-
-const octokit = getOctokit(GITHUB_TOKEN);
-
-const TEST_BRANCH_PREFIX = `test-${randomBytes(4).toString("hex")}`;
+const octokit = getOctokit(ENV.GITHUB_TOKEN);
 
 const TEST_BRANCHES = {
-  COMMIT_FILE: `${TEST_BRANCH_PREFIX}-commit-file`,
+  COMMIT_FILE: `${ROOT_TEST_BRANCH_PREFIX}-fs-commit-file`,
 } as const;
 
 describe("fs", () => {
   describe("commitFilesFromDirectory", () => {
     it("should commit a file", async () => {
       // Create test directory
-      const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), "test-"));
+      await fs.mkdir(ROOT_TEMP_DIRECTORY, { recursive: true });
+      const tmpDir = await fs.mkdtemp(path.join(ROOT_TEMP_DIRECTORY, "test-"));
       await fs.writeFile(path.join(tmpDir, "foo.txt"), "Hello, world!");
 
       await commitFilesFromDirectory({
         octokit,
-        owner,
-        repository,
+        ...REPO,
         branch: TEST_BRANCHES.COMMIT_FILE,
         baseBranch: "main",
         message: {
@@ -73,31 +47,6 @@ describe("fs", () => {
   afterAll(async () => {
     console.info("Cleaning up test branches");
 
-    await Promise.all(
-      Object.values(TEST_BRANCHES).map(async (branch) => {
-        console.debug(`Deleting branch ${branch}`);
-        // Get Ref
-        const ref = await getRepositoryMetadata(octokit, {
-          owner,
-          name: repository,
-          ref: `refs/heads/${branch}`,
-        });
-
-        const refId = ref?.ref?.id;
-
-        if (!refId) {
-          console.warn(`Branch ${branch} not found`);
-          return;
-        }
-
-        await deleteRefMutation(octokit, {
-          input: {
-            refId,
-          },
-        });
-
-        console.debug(`Deleted branch ${branch}`);
-      }),
-    );
+    await deleteBranches(octokit, Object.values(TEST_BRANCHES));
   });
 });
diff --git a/src/test/integration/jest.globalTeardown.ts b/src/test/integration/jest.globalTeardown.ts
new file mode 100644
index 0000000..926531a
--- /dev/null
+++ b/src/test/integration/jest.globalTeardown.ts
@@ -0,0 +1,12 @@
+import { promises as fs } from "fs";
+import { Config } from "jest";
+
+module.exports = async (_: unknown, projectConfig: Config) => {
+  const directory = projectConfig.globals?.ROOT_TEMP_DIRECTORY;
+  if (!(typeof directory == "string")) {
+    throw new Error("ROOT_TEMP_DIRECTORY must be set");
+  }
+  console.log(`Deleting directory: ${directory}`);
+
+  await fs.rm(directory, { recursive: true });
+};
diff --git a/src/test/integration/node.test.ts b/src/test/integration/node.test.ts
new file mode 100644
index 0000000..9b0ab87
--- /dev/null
+++ b/src/test/integration/node.test.ts
@@ -0,0 +1,60 @@
+import { getOctokit } from "@actions/github/lib/github.js";
+
+import { ENV, REPO, ROOT_TEST_BRANCH_PREFIX, log } from "./env.js";
+import { commitFilesFromBuffers } from "../../node.js";
+import { deleteBranches } from "./util.js";
+
+const octokit = getOctokit(ENV.GITHUB_TOKEN);
+
+const TEST_BRANCH_PREFIX = `${ROOT_TEST_BRANCH_PREFIX}-node`;
+
+describe("node", () => {
+  const branches: string[] = [];
+
+  // Set timeout to 1 minute
+  jest.setTimeout(60 * 1000);
+
+  describe("commitFilesFromBuffers", () => {
+    describe("can commit single file of various sizes", () => {
+      const SIZES_BYTES = {
+        "1KiB": 1024,
+        "1MiB": 1024 * 1024,
+        "10MiB": 1024 * 1024 * 10,
+      };
+
+      for (const [sizeName, sizeBytes] of Object.entries(SIZES_BYTES)) {
+        it(`Can commit a ${sizeName}`, async () => {
+          const branch = `${TEST_BRANCH_PREFIX}-${sizeName}`;
+          branches.push(branch);
+          const contents = Buffer.alloc(sizeBytes, "Hello, world!");
+
+          await commitFilesFromBuffers({
+            octokit,
+            ...REPO,
+            branch,
+            baseBranch: "main",
+            message: {
+              headline: "Test commit",
+              body: "This is a test commit",
+            },
+            fileChanges: {
+              additions: [
+                {
+                  path: `${sizeName}.txt`,
+                  contents,
+                },
+              ],
+            },
+            log,
+          });
+        });
+      }
+    });
+  });
+
+  afterAll(async () => {
+    console.info("Cleaning up test branches");
+
+    await deleteBranches(octokit, branches);
+  });
+});
diff --git a/src/test/integration/util.ts b/src/test/integration/util.ts
new file mode 100644
index 0000000..5a52271
--- /dev/null
+++ b/src/test/integration/util.ts
@@ -0,0 +1,37 @@
+import {
+  deleteRefMutation,
+  getRepositoryMetadata,
+  GitHubClient,
+} from "../../github/graphql/queries.js";
+import { REPO } from "./env.js";
+
+export const deleteBranches = async (
+  octokit: GitHubClient,
+  branches: string[],
+) =>
+  Promise.all(
+    branches.map(async (branch) => {
+      console.debug(`Deleting branch ${branch}`);
+      // Get Ref
+      const ref = await getRepositoryMetadata(octokit, {
+        owner: REPO.owner,
+        name: REPO.repository,
+        ref: `refs/heads/${branch}`,
+      });
+
+      const refId = ref?.ref?.id;
+
+      if (!refId) {
+        console.warn(`Branch ${branch} not found`);
+        return;
+      }
+
+      await deleteRefMutation(octokit, {
+        input: {
+          refId,
+        },
+      });
+
+      console.debug(`Deleted branch ${branch}`);
+    }),
+  );
diff --git a/tsup.config.ts b/tsup.config.ts
index 00fa86f..2a0b31c 100644
--- a/tsup.config.ts
+++ b/tsup.config.ts
@@ -1,7 +1,7 @@
 import { defineConfig } from "tsup";
 
 export default defineConfig({
-  entry: ["src/index.ts", "src/fs.ts"],
+  entry: ["src/index.ts", "src/core.ts", "src/fs.ts", "src/node.ts"],
   format: ["cjs", "esm"],
   dts: true,
 });