Inspect every
request.
Fix bugs faster.
Geiger is a modern, privacy-first HTTP/S traffic inspector for developers and QA engineers. Capture, decrypt, modify, and replay web traffic on Windows, macOS, and Linux.
Trusted by developers at
50,000+
developers worldwide
Everything you need.
Nothing you don't.
Built by developers tired of bloated, slow debugging tools. Every feature earns its place.
HTTPS Decryption
Inspect encrypted traffic with automatic certificate management. No manual setup — Geiger handles CA installation and decryption transparently.
Real-Time Traffic Capture
See every HTTP/S, WebSocket, and gRPC request as it happens — from browser, mobile, desktop apps, or any connected device.
Request Composer
Build, modify, and replay any HTTP request from scratch. Import from captured traffic, tweak headers, body, and auth — then fire it instantly.
Rules Engine
Intercept and modify traffic on the fly. Rewrite URLs, inject headers, mock responses, simulate latency — without touching a single line of code.
Remote Device Capture
Set Geiger as a proxy on iOS or Android and inspect mobile app traffic with full HTTPS decryption. Our setup wizard takes under 2 minutes.
JavaScript Scripting
Automate debugging workflows with a built-in JS scripting engine. Transform requests, run assertions, or integrate with your CI/CD pipeline.
Privacy-First by Design
All traffic stays on your machine. No telemetry, no cloud sync, no accounts required for the free tier. Your data is yours — period.
HAR & JSON Export
Export captured sessions as HAR, JSON, or cURL. Share traffic snapshots with teammates or attach to bug reports.
Modify traffic without touching your codebase.
Geiger's visual rules engine lets you intercept any request or response and transform it on the fly — no code changes required. Simulate errors, inject auth headers, delay responses, or redirect to staging in seconds.
- Rewrite URLs, headers, and body content
- Simulate 4xx/5xx error responses
- Inject latency to test timeouts
- Block specific endpoints to test fallbacks
- Export rules as JSON and share with your team
Inject Auth Header
/api/*
Mock 500 on /checkout
/api/checkout
Redirect to staging
api.prod.com/*
Delay /search 2s
/api/search
See exactly what's being sent — and why.
Geiger's inspector gives you the full picture: raw headers, decoded body, cookies, timing breakdown, and decoded JWT tokens — all in one panel. Click any request to explore it, no switching between tabs.
- Full request & response body with syntax highlighting
- Automatic JWT & cookie decoding
- Timing waterfall (DNS, connect, TTFB, transfer)
- Side-by-side request diff / compare
- One-click copy as cURL, fetch, or Axios
Up and debugging
in 60 seconds.
Download & Launch
Install Geiger on Windows, macOS, or Linux. No dependencies, no account required. Up and running in under 60 seconds.
Set Proxy & Capture
Point your browser, app, or device at Geiger's proxy. Watch HTTP/S traffic appear in real time with full request and response bodies.
Inspect, Modify & Fix
Filter, search, and drill into any request. Replay it, modify headers, mock responses — and ship the fix.
Ready to start debugging?
Download Geiger for your platform. Free forever, no account required.
v0.9.1-beta · ~28MB · MIT licensed core
Geiger vs. Fiddler Everywhere
An honest, feature-by-feature comparison.
Comparison based on publicly available feature lists. Last updated May 2026.
Simple, honest pricing.
No surprise upsells. Cancel anytime.
Free
Perfect for individual developers and open source projects.
- Unlimited HTTP/S capture
- HTTPS decryption
- Request composer
- Basic filters & search
- HAR & JSON export
- Windows, macOS, Linux
- Community support
Pro
For professional developers and QA teams who need the full toolkit.
- Everything in Free
- Advanced Rules Engine
- JavaScript scripting
- Remote device capture
- Traffic comparison (diff)
- Mock server & response templates
- Team session sharing
- Priority email support
Enterprise
For large teams with compliance, security, and integration requirements.
- Everything in Pro
- On-premise deployment
- SOC 2 compliance
- Custom CA & certificate management
- CI/CD API integration
- Dedicated onboarding & SLA
- Invoice billing
Common questions.
Stop guessing.
Start inspecting.
Download Geiger free and see exactly what your application is doing on the wire — in the next 60 seconds.
No account required · Works offline · MIT licensed core