Caido is a web application security testing toolkit built around an intercepting proxy, positioned as a modern alternative to Burp Suite for manual penetration testing. It pairs a Rust backend with a clean, browser-based UI.
Over 2025 and into 2026 it became the tool the Burp-alternative conversation keeps returning to, ranking among the top organic results for “burp suite alternative” and appearing across bug bounty and pentest communities.
Caido’s own figures put its community at 7,000+ active hackers, 58+ community plugins, and 4,500+ Discord members.
Caido targets pentesters, bug bounty hunters, and security engineers who find Burp heavy and want a faster, more modern workflow.
What Is Caido?
Caido is an intercepting proxy for web security testing. You route browser or client traffic through it, then intercept, inspect, replay, and tamper with HTTP requests to probe an application for vulnerabilities.
Unlike a traditional desktop tool, Caido runs as a backend you reach from a browser. You can run it locally or host the instance on a server and connect remotely, which suits both solo testers and teams.
Caido organizes each engagement as a separate project; the left sidebar holds the proxy, Replay, Automate, Workflows, and Assistant tooling.
| Feature | Details |
|---|---|
| Type | Intercepting proxy / manual web security testing |
| Backend | Rust, with a browser-based UI |
| Filtering | HTTPQL query language for requests, responses, and metadata |
| Automation | Node-based Workflows for ad-hoc request processing |
| Extensibility | Plugin store with community and AI-assisted plugins |
| AI | Bring-your-own-model plugins and a Client SDK for AI agents |
| Deployment | Local or self-hosted server instance |
| Pricing | Free Basic tier; paid Individual, Team, Enterprise plans |
What are Caido’s key features?
Intercepting proxy and replay
The core workflow mirrors what pentesters expect from a proxy: intercept requests, inspect them, replay them with modifications, and observe how the application responds. The browser-based UI keeps proxy history, Replay tabs, and findings in one place.
HTTPQL filtering
Caido ships a query language, HTTPQL, for filtering requests, responses, and metadata. Queries use namespaces and operators, so you write resp.code.gte:400 to find error responses or req.host.eq:"api.example.com" to isolate one host.
You can filter live traffic as it passes through the proxy or query a project’s full history, then save common queries as reusable presets.
Workflows
Caido’s Workflows system lets you build ad-hoc automation with a node-based editor. Instead of writing scripts, you chain processing steps to transform, match, or react to requests as they pass through the proxy.
Plugins and AI
A plugin store extends Caido with community-built and AI-assisted plugins. You connect your own model provider — Anthropic, Google, OpenAI, or others through OpenRouter — and a Client SDK gives AI agents programmatic access to the proxy.
Projects
Engagements are organized into projects, keeping the history, scope, and findings for each target separate. This project-based model is one reason testers running many concurrent engagements adopt it.
Pricing
Caido offers a free Basic tier that never expires, capped at 2 projects, 7 workflows, 3 plugins, and 5 filter presets, with HTTPQL filtering and the core HTTP tools included.
Paid Individual, Team, and Enterprise plans lift those limits and add shared instances, centralized billing, and priority support. Students and teachers at accredited institutions can apply for a free one-year education license.
Caido vs Burp Suite
Caido and Burp Suite overlap most on the manual testing workflow, since both center on an intercepting proxy with request replay and tampering. Caido leans on interface speed and a modern, browser-based experience.
Burp Suite Professional carries a larger extension ecosystem through its BApp Store, an automated scanner, and Burp Collaborator for out-of-band detection. Caido is the lighter, manual-first option; Burp is the heavier, more complete toolkit.
For broader options, see the Burp Suite alternatives and ZAP alternatives comparisons, plus the full DAST tools category.
When to use Caido
Caido fits pentesters and bug bounty hunters who want a fast, modern manual proxy without the weight of a full enterprise toolkit.
If your workflow is manual exploration — intercept, replay, tamper, repeat — Caido covers it cleanly, and the free Basic tier makes it easy to try. Teams running many engagements benefit from its project model and server-hosted deployment.
If you need a full automated scanner, deep extension ecosystem, or out-of-band detection, a tool like Burp Suite Professional or ZAP remains the better fit.