Security

ReDoS (Regular Expression Denial of Service) Scanner

Scan one or more regex patterns for catastrophic backtracking risk, simulate evil inputs, and suggest safer rewrites

json· JSON resultOpen tool

Quick start

Call this tool from your code in three languages.

cURL

curl -X POST 'https://api.elysiatools.com/en/api/tools/redos-regex-scanner' \
  -H 'Content-Type: application/json' \
  -d '{"regexList":"(a+)+$\n^(\\w+\\s?)*$","flags":"","maxEvilInputLength":32,"simulationRuns":200}'

API reference

Send a POST request with your inputs as JSON. File parameters require a separate upload first.

Endpoint

HTTP

POST https://api.elysiatools.com/en/api/tools/redos-regex-scanner

Parameters

Name	Type	Required	Description
regexList	textarea	Yes	—
flags	text	No	—
maxEvilInputLength	number	No	—
simulationRuns	number	No	—

Response format

JSON result

JSON

{
  "key": {...},
  "metadata": {
    "key": "value"
  },
  "error": "Error message (optional)",
  "message": "Notification message (optional)"
}

MCP integration

Add this tool to your Model Context Protocol server so AI agents can list and call it.

Server configuration

Add this block to your MCP client configuration:

mcp.json

{
  "mcpServers": {
    "elysiatools-redos-regex-scanner": {
      "name": "redos-regex-scanner",
      "description": "Scan one or more regex patterns for catastrophic backtracking risk, simulate evil inputs, and suggest safer rewrites",
      "baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=redos-regex-scanner",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

List available tools

After connecting to the SSE endpoint, list the exposed tools:

tools/list

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list"
}

Call this tool

Invoke the tool by its id, passing arguments built from its parameters:

tools/call

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "redos-regex-scanner",
    "arguments": {
  "regexList": "(a+)+$\n^(\\w+\\s?)*$",
  "flags": "",
  "maxEvilInputLength": 32,
  "simulationRuns": 200
}
  }
}

Chain multiple tools in one session with a comma-separated toolId list, e.g. /mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp (max 20).

Questions or issues? Contact [email protected]

Browse tools Open tool

curl -X POST 'https://api.elysiatools.com/en/api/tools/redos-regex-scanner' \ -H 'Content-Type: application/json' \ -d '{"regexList":"(a+)+$\n^(\\w+\\s?)*$","flags":"","maxEvilInputLength":32,"simulationRuns":200}'

Name

Type

Required

Description

regexList

textarea

Yes

—

flags

text

—

maxEvilInputLength

number

—

simulationRuns

number

—

{ "mcpServers": { "elysiatools-redos-regex-scanner": { "name": "redos-regex-scanner", "description": "Scan one or more regex patterns for catastrophic backtracking risk, simulate evil inputs, and suggest safer rewrites", "baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=redos-regex-scanner", "command": "", "args": [], "env": {}, "isActive": true, "type": "sse" } } }

{ "jsonrpc": "2.0", "id": 2, "method": "tools/call", "params": { "name": "redos-regex-scanner", "arguments": { "regexList": "(a+)+$\n^(\\w+\\s?)*$", "flags": "", "maxEvilInputLength": 32, "simulationRuns": 200 } } }