API Validator
Validate API requests, responses, and schemas instantly
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How much of your last endpoint was just checking that the input was sane? Have you ever shipped a POST route that trusted an email field nobody looked at? API Validator on EizTools takes a plain description of an endpoint and hands back the route with its validation rules, error responses and example payloads already written.
Short answer: API Validator is a free AI tool on EizTools that turns a written endpoint description into route code with input validation, error handling and sample requests included. Pick your framework, API style and auth method, then generate.
What is API Validator?
API Validator is a code generator aimed at the part of an endpoint most people rush. The prompt box asks for the resource, the methods and the fields. Say you are building a bookings endpoint with a property, dates, a guest count and an email. Describe it, choose your stack, and API Validator writes the route with the checks around it.
A rule for every field
Each field gets a type check and a limit, including the ones you would have skipped.
Written for your stack
The output follows the framework you pick, so it reads like your codebase.
Docs and tests together
Turn on the extras and one run returns reference notes and test cases too.
Why Hand Written Checks Keep Slipping Through
Validation is dull to write and easy to half finish. You remember the email format. You forget the guest count can arrive as a string, as zero, or as four hundred. That lands in production as a 500 instead of a clean 422. There is a second cost: the rules get written in the route and again in the docs, and the two drift apart.
How Does API Validator Work?
- Describe the endpoint, including anything the request must reject.
- Pick an AI model from the selector.
- Open the advanced options and set framework, API style, auth and output.
- Press Generate. The output card shows the code with a word count and reading time.
- Copy it, or download it as TXT, Word or HTML. Recent runs stay in the activity history panel.
A description this short is already enough to work with:
POST /bookings
fields: property_id (int, required), check_in (date), nights (int, 1 to 30),
guest_email (email), notes (string, optional, max 500)
reject overlapping dates for the same propertySetting Framework, Auth And Detail Level
Four dropdowns do most of the work. Each starts on None, leaving the choice to the model.
| Option | What it controls | Good starting point |
|---|---|---|
| Language / Framework | The stack the code is written for | Laravel or Python / FastAPI when you know the target |
| API Style | The shape of the endpoint | REST, unless you are really on GraphQL |
| Auth | The auth layer the route assumes | JWT inside a service, API Key for partners |
| Output | How much comes back with the code | Code + Docs, so rules and reference agree |
Under those sit four toggles: Include Validation, Include Error Handling, Include Examples and Include Docs. A Detail Level slider runs from 1 to 100 percent, and a Custom Instructions box takes house rules such as your error envelope.
Worth knowing The tool writes the validation layer, it does not send live requests to your server. Treat the result as a first draft and run it against your own tests.
What To Type In The Prompt Box
Vague input gets a generic route back. The bookings example works because it names types and limits. Include:
- ✅ The method and the path
- ✅ Every field, with its type and whether it is required
- ✅ The limits that matter, such as a maximum length or a date range
- ✅ The requests that must fail, and the status code you want back
Say what should break, not only what should work. That habit changes the output more than any dropdown.
EizTools is a free AI tools platform with a dedicated workspace for each job rather than one general chat box. Every tool runs without an account, a credit counter or a paid tier, and you choose the AI model from the selector before each generation. When the generated route throws something you did not expect, paste the stack trace into Error Fixer and carry on from there.
Frequently Asked Questions
Does API Validator test a live API?
No. It works from your written description, not from network calls. Nothing is sent to your server and no credentials are needed, so you can use it before deployment.
Which frameworks can it write for?
Node / Express, Python / FastAPI, Django, Laravel, Spring, Go, Ruby on Rails and .NET, plus an Auto setting that lets the model choose from your description.
Can it produce a spec instead of code?
Yes. Set Output to Spec / Schema for the definition rather than a route. Code + Tests is there too when you want cases alongside the endpoint.
Is API Validator free to use?
Yes, and there is no sign up wall on the tool. Open the page, describe the endpoint and generate. Nothing is metered and no card is asked for.
Most endpoints fail on the input, not on the logic. API Validator hands you that half already written, with the failure cases named instead of assumed. Describe your next route in the box above, and browse Coding Tools for the step after it.
Sabir Bepari
Founder of EizTools and a passionate AI enthusiast dedicated to building practical, user-friendly AI tools that simplify everyday tasks.
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