# regex101

A browser editor for writing, testing and debugging regular expressions in ten engine flavors, with a plain-English breakdown of each token, match details, substitution, unit tests and shareable saved versions.

- Category: Developer utilities · by Firas Dib
- Website: https://regex101.com/
- Live data: no
- Checked on the official pages: 2026-10-23

## API

- Official API: yes, docs https://regex101.com/api/docs
- Key needed: no
- Price: Free tier
- Base URL: https://regex101.com/api/
- Formats: json

Example request:

```
https://regex101.com/api/library?search=email&orderBy=MOST_UPVOTES
```

## Data and license

- License: site terms (https://docs.regex101.com/legal/terms-and-conditions/); covers Terms cover the regex101 service; they do not say who owns regexes or generated code you write in it. Reselling or exploiting the service needs written permission.
- Commercial use unclear
- Credit: not stated
- Embedding unclear
- Quote (api_official): "regex101 is an interactive regular expression editor, tester, debugger, and sharing service with an OpenAPI-documented HTTP API." (https://regex101.com/llms.txt)
- Quote (api_scope): "Most matching and substitution work runs in the interactive application. The HTTP API primarily manages saved workspaces, accounts, library entries, quizzes, and ReDoS analysis." (https://regex101.com/llms.txt)
- Quote (api_key): "Authentication is optional for public workspaces and required when the requested workspace is private." (https://docs.regex101.com/application/api/)
- Quote (api_example): "curl --fail-with-body "https://regex101.com/api/workspace/$WORKSPACE_ID/$WORKSPACE_VERSION"" (https://docs.regex101.com/application/api/)
- Quote (api_library): "summary: Get library entries using cursor-based pagination" (https://regex101.com/api/openapi.yaml)
- Quote (api_price): "More than two test strings requires Pro on regex101.com." (https://docs.regex101.com/application/api/)
- Quote (mcp): "Use the remote MCP server at `https://regex101.com/mcp`. It provides tools to get, save, update, delete, title, tag, and explain regex workspaces." (https://regex101.com/llms.txt)
- Quote (commercial_service): "You agree not to reproduce, duplicate, copy, sell, resell, or exploit any portion of the Service," (https://docs.regex101.com/legal/terms-and-conditions/)
- Quote (scraping): "to spam, phish, pharm, pretext, spider, crawl, or scrape" (https://docs.regex101.com/legal/terms-and-conditions/)
- Quote (self_hosted): "Enterprise gives your team the editor, saved workspaces, accounts, and licensed integrations in a deployment you operate." (https://docs.regex101.com/enterprise/licenses/)
- Quote (self_hosted_license): "A standard license covers one running instance and the individual users specified on the invoice." (https://docs.regex101.com/enterprise/licenses/)
- Quote (parser_license): "The parser is licensed separately from regex101 Pro and self-hosted regex101." (https://docs.regex101.com/regex-parser/pricing/)
- Quote (open_source): "This repository is currently only used for issue tracking for https://regex101.com" (https://github.com/firasdib/Regex101)

## Rules for an agent

- Not open source (GitHub repo is an issue tracker only) and no free npm/PyPI package: the TypeScript regex parser is a separately licensed commercial product and self-hosting is a paid Docker-image Enterprise license. The API mainly reads/writes saved workspaces (public reads need no token; live OpenAPI at /api/openapi.yaml); matching runs in the browser, so test regexes locally in your target language.
- Do not scrape or crawl the site; use the documented API or the MCP server
- Never put bearer tokens in URLs or logs; private workspaces need a signed-in token
- Do not resell or repackage the service without written permission

## Agent access

- llms.txt: https://regex101.com/llms.txt
- MCP: https://regex101.com/mcp

Human page: https://agentgid.com/resources/regex101/
Source: AgentGid (agentgid.com). Facts are quoted from the site's own pages; check the license page before you ship.