HAR to OpenAPI
Paste a HAR capture and get a draft OpenAPI 3.x spec — endpoints, methods, path/query params, and inferred request/response JSON schemas. Runs entirely in your browser; nothing is uploaded.
About this HAR to OpenAPI converter
This tool turns a HAR (HTTP Archive) capture — the network log your browser's
DevTools can export — into a draft OpenAPI 3.x specification, entirely in your
browser. Point it at the traffic an app or SPA actually made and get a starting
openapi.yaml (or openapi.json) describing the endpoints it hit, without writing
the spec by hand.
It reads log.entries, groups the requests by path and HTTP method, derives the
servers base URL from the request origins, and infers a JSON Schema for each
request body and for each response status code from the captured JSON. Id-like path
segments are collapsed into {param} templates so /users/1 and /users/2 become a
single /users/{user} operation.
How to capture a HAR
- Open your browser's DevTools → Network tab.
- Reload the page or click through the flows you want documented.
- Right-click any request → Save all as HAR (or use the download/export button).
- Paste the saved JSON into the box above.
What it infers
- Paths & methods — one operation per
(path, method)seen in the capture. - Servers — the distinct
scheme://hostorigins becomeserversentries. - Path parameters — numeric ids, UUIDs, and long opaque tokens are templated
into
{param}and named after the preceding collection segment (/users/{user}). - Query parameters — collected from the URL and the HAR
queryStringarray. - Request bodies — JSON post data becomes a
requestBodyschema. - Responses — one entry per observed status code, each with a schema (and, for JSON, an example) inferred from the captured body.
Options
- Output format — YAML (default) or JSON. Both encode the same document.
- OpenAPI version — stamp
3.0.3or3.1.0. - Parameterize id-like path segments — on by default; turn it off to keep every literal URL as its own path.
- Infer scalar parameter types — type query/path params as
integer,number, orbooleanfrom their values; off makes every param astring. - Include captured examples — attach a real captured value to each parameter and body schema; turn it off for a schema-only spec.
- Host filter — a case-insensitive substring to keep only requests to one host, handy for stripping analytics/CDN noise from a mixed capture.
- API title — set
info.title; blank infers it from the first host. - Drop operations without a 2xx response — remove error-only or never-completed calls from the output.
The result is a deterministic best-effort draft meant as a head start, not a finished contract — review and edit it before publishing.
FAQ
Does my HAR get uploaded anywhere?
No. The conversion runs as WebAssembly inside your browser tab — the HAR you paste never leaves your machine, and there is no server, account, or network call involved.
Will this redact passwords, tokens, or cookies for me?
No — a HAR routinely contains secrets (auth headers, cookies, tokens, request bodies), and this tool does not strip them. If your capture is sensitive, run it through the har-redact tool first, then convert the cleaned HAR here.
How accurate is the generated spec?
It is a draft inferred purely from what the capture happened to show. A field only appears if it was present in a captured body, an endpoint only appears if it was called, and types are guessed from example values. Treat it as a scaffold to review and refine, not as a validated, authoritative contract.
Why did two different URLs collapse into one path?
With Parameterize id-like path segments on (the default), segments that look like
ids — all-digit numbers, UUIDs, and long opaque tokens — are replaced with a
{param} template, so /orders/1001 and /orders/1002 merge into
/orders/{order}. Turn the option off to keep each literal URL as a separate path.
Does it detect authentication or security schemes?
No. Guessing securitySchemes from headers is noisy and easily wrong, so the tool
deliberately skips it. Add your API's auth definitions by hand after generating the
draft.
Can I get JSON instead of YAML, or a specific OpenAPI version?
Yes. Set Output format to JSON for openapi.json, and choose OpenAPI version
3.0.3 or 3.1.0. Both formats and versions describe the same inferred document.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool har-to-openapi '{ "log": { "entries": [ … ] } }'New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/har-to-openapi/?har=%7B%20%22log%22%3A%20%7B%20%22entries%22%3A%20%5B%20%E2%80%A6%20%5D%20%7D%20%7D&format=yaml&openapi_version=3.0.3¶meterize_paths=true&infer_types=true&include_examples=true&domain=api.example.com&title=My%20API&drop_unsuccessful=trueMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.