AI API Payload Mocking Tool
Generate realistic mock API responses from OpenAPI spec, JSON sample, or described endpoint. Pure-JS faker-style data (names, emails, phones, UUIDs, dates, addresses), CRUD route config, latency/error/status simulation, scenario presets (empty/error/large/paginated), Mockoon-style export, optional BYO-key LLM enhancement. 100% client-side — nothing uploaded.
About AI API Payload Mocking Tool
Generate realistic mock API responses from OpenAPI spec, JSON sample, or described endpoint. Pure-JS faker-style data (names, emails, phones, UUIDs, dates, addresses), CRUD route config, latency/error/status simulation, scenario presets (empty/error/large/paginated), Mockoon-style export, optional BYO-key LLM enhancement. 100% client-side — nothing uploaded. Everything runs locally in your browser — your data never leaves your device.
How to use
- Enter your input in the tool above.
- Adjust any options to your preference.
- Use the Copy or Download buttons to save the result.
- Everything happens locally — your data never leaves your browser.
FAQ
How does the API payload mocking tool work?
Paste an OpenAPI/Swagger spec, a JSON sample, or describe an endpoint in plain English. The tool parses the schema, infers realistic mock values using a built-in faker (names, emails, phones, UUIDs, dates, addresses, URLs), and produces a mock-response config + CRUD routes you can copy/export. You can also generate a fetch-able mock handler to serve mocks in-browser.
What types of mock data can it generate?
Person names, first/last names, usernames, emails, phone numbers (US/UK/intl formats), street addresses, cities, states, zip codes, countries, UUIDs (v4), ISO-8601 dates, timestamps, booleans, integers in range, floats, currency amounts, URLs, slugs, hex colors, IP addresses (v4/v6), user-agents, lorem-ipsum sentences/paragraphs, payment-card numbers (Luhn-valid), and JSON nested from any schema.
Can I simulate latency, errors, and pagination?
Yes. Configure per-route latency (ms), status code (200/201/400/404/500/etc.), and pick from scenario presets: empty result, error response, large list (1k items), paginated response, or single resource. The exportable config includes these so your mock server behaves realistically.
Can I use my own LLM API key for smarter mocks?
Yes. The tool builds an optimal prompt from your spec/sample and optionally calls OpenAI/Anthropic (with a key you paste — stored only in localStorage on this device). If no key is provided, the pure-JS template/faker engine produces deterministic, realistic mock data offline.
What extra features does this tool have compared to others?
(1) OpenAPI/Swagger JSON parser. (2) JSON-sample schema inference. (3) Plain-English endpoint describer. (4) Pure-JS faker (20+ data types). (5) CRUD route generator (list/get/create/update/delete). (6) Latency + status-code + scenario presets. (7) Mockoon/OpenAPI-compatible config export. (8) In-browser fetch-mock handler. (9) Request inspector. (10) Optional BYO-key LLM enhancement. (11) History (localStorage, last 20). (12) Shareable URL. (13) Paginated response builder. (14) Luhn-valid card generator. (15) Locale-aware names/phones.
Is my data sent anywhere?
No. All parsing, mocking, and faker generation run locally in your browser. The only network call is if you paste your own LLM API key and click 'Enhance with LLM' — that request goes directly from your browser to the LLM provider you choose. Specs, samples, and history never leave this device.
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