Metlo is an open source API security tool you can setup in < 15 minutes that inventories your endpoints, detects bad actors and blocks malicious traffic in real time.

With Metlo you can:

  • Detect API attacks in real time.
  • Automatically block malicious actors.
  • Create an Inventory of all your API Endpoints and Sensitive Data.
  • Proactively test your APIs before they go into production.


  • Endpoint Discovery - Metlo scans network traffic and creates an inventory of every single endpoint in your API.
  • Sensitive Data Scannning - Each endpoint is scanned for PII data and given a risk score.
  • Vulnerability Discovery - Get Alerts for issues like unauthenticated endpoints returning sensitive data, No HSTS headers, PII data in URL params, Open API Spec Diffs and more
  • API Security Testing - Build security tests directly in Metlo with a simple HTTP Request editor and javascript assertions.
  • CI/CD Integration - Integrate with your CI/CD to find issues in development and staging.
  • Attack Detection - Our ML Algorithms build a model for baseline API behavior. Any deviation from this baseline is surfaced to your security team as soon as possible.
  • Attack Context - Metlo’s UI gives you full context around any attack to help quickly fix the vulnerability.

API Testing

  • Metlo’s suite of automated tests and our security testing framework let you find vulnerabilities in development.
  • Our built in testing framework helps you get to 100% Security Coverage on your highest risk APIs
  • Integrates directly with your CI/CD 3808

We’re Hiring!

We would love for you to come help us make Metlo better. Come join us at Metlo!

Open-source vs. paid

This repo is entirely MIT licensed. Features like user management, user roles and attack protection require an enterprise license. Contact us for more information.


Checkout our development guide for more info on how to develop Metlo locally.