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fastapi.online — Regex Pattern Generator
x402
fastapi.online — Regex Pattern Generator is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.0015/call, status unknown (last checked 2026-09-14).
Generates a regular expression pattern from a natural language description, with optional flavor/dialect selection
Price / call$0.0015
Success—
StatusUnknown
How this service works
Chat, embeddings, OCR, speech-to-text, image editing, image understanding (captioning/Q&A), text-to-speech, translation, writing tools, classification tools, developer tools, local utilities, format/checksum validators, encoding & crypto utilities, date/time calculators, geo/coordinate math, math & finance calculators, novelty tools, and business/social writing generators — 179 endpoints in all, across multiple specialized self-hosted models. Pay per call with crypto — no signup — or get an API key.
Output
A generated regular expression pattern matching the provided description, optionally tailored to the specified regex flavor or dialect (e.g. Python, PCRE, JavaScript).
Example use cases
Email validation regex for form
“I need a Python-flavor regex that matches valid email addresses — something like user@domain.com format with no spaces.”
Log parsing pattern from description
“Generate a regex in PCRE flavor that captures a timestamp and log level from lines like '2024-01-15 ERROR: something failed'.”
Input sanitization for phone numbers
“Write me a JavaScript-flavor regex that matches US phone numbers in formats like (555) 123-4567 or 555-123-4567.”
Technical details
Endpoint
POSThttps://api.fastapi.online/regex-generateWhen to prefer
Use this endpoint when you need to quickly generate a regular expression from a plain-English description without writing it manually — especially useful for developers who know what they want to match but not the exact regex syntax, or for agents automating code generation tasks. Choose this over generic LLM chat when you want a pay-per-call, no-signup solution with flavor-specific output.
Side effects
- Description too vague to produce a meaningful pattern
- Unsupported or unrecognized flavor value returns error
- Description exceeds 2000 character limit
- Empty or missing description field returns validation error
- Generated regex may not perfectly match all edge cases of the described pattern
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| flavor | string | |
| description | string |
Tags
x402
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