fetch-har

library12.0.4jsnpmunverified

Make a fetch request from a HAR (HTTP Archive) definition. Current stable version is 12.0.4, requiring Node >=22 and ESM. Converts HAR log entries into native fetch() calls, supporting Node 18+ and all browsers with native fetch. Key differentiators: no polyfills needed, works across browsers and Node, supports file uploads from buffers or File objects, and integrates with mocking libraries like nock or MSW. Maintained by readme.io with cross-browser CI testing.

testing

npm install fetch-har

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · FETCH-HAR

fetch-har

testingjavascriptv12.0.4

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

fetchHAR

✓ import fetchHAR from 'fetch-har'

✗ import { fetchHAR } from 'fetch-har'

Default export only; named import will be undefined. ESM-only, no CommonJS.

fetchHAR

✓ import fetchHAR from 'fetch-har'

✗ const fetchHAR = require('fetch-har')

Package is ESM-only since v12 (Node >=22). require() will throw ERR_REQUIRE_ESM.

fetchHAR

✓ import type { Options } from 'fetch-har'

TypeScript types are included. Options type can be imported for customizing requests.

Demonstrates importing fetch-har, constructing a HAR object with an Authorization header, calling fetchHAR, and parsing the JSON response.

import fetchHAR from 'fetch-har'; const har = { log: { entries: [ { request: { method: 'GET', url: 'https://httpbin.org/get', headers: [ { name: 'Authorization', value: 'Bearer ' + (process.env.API_KEY ?? '') }, ], }, }, ], }, }; const response = await fetchHAR(har); const data = await response.json(); console.log(data);

Debug

Known issues

breakingNode >=22 required (v12+). Node 18 or 20 will not work.

fix

Upgrade Node to v22 or later, or downgrade fetch-har to v11.x.

affects: >=12.0.0

gotchafiles option is required for file uploads unless the HAR contains data URLs. Missing both causes a fatal exception.

fix

Always provide a files map when dealing with multipart/form-data HAR entries without data URLs.

affects: *

gotchaThe init option's body and credentials may be overridden by the HAR definition.

fix

Do not rely on custom body/credentials in init if the HAR specifies them.

affects: *

Errors

Common errors & fixes

ERR_REQUIRE_ESM

Using CommonJS require() on an ESM-only package.

fix

Use import statement or set type: module in package.json.

TypeError: fetchHAR is not a function

Named import instead of default import: import { fetchHAR } from 'fetch-har'.

fix

Use default import: import fetchHAR from 'fetch-har'.

Error: No files provided for multipart/form-data and no data URL found for parameter 'file'. Fatal exception thrown.

Missing files option or data URL in HAR for a file upload parameter.

fix

Provide a files map with a buffer/File for the parameter name, or add a data URL to the HAR entry.

Upgrade

Version history

12.0.4latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

5 hits · last 30 days

node

Resources

githubssh://git@github.com/readmeio/fetch-har ↗

packagefetch-har ↗

homepagehttps://github.com/readmeio/fetch-har#readme ↗