Fast CORS Unblocker - Instant API Toggle
0ms Declarative CORS Header Injector with Smart Localhost Safe-Mode for Frontend & API Developers
Technical Highlights
- 1-Click Master Toggle to Bypass CORS with 0ms Latency
- Smart Localhost Safe-Mode: Zero impact on normal browsing or streaming
- Manifest V3 Native declarativeNetRequest Architecture (0% JS packet sniffing)
- Full Credentials & Authentication Cookie Support (Allow-Credentials: true)
- Preflight OPTIONS Caching & All HTTP Methods (GET, POST, PUT, DELETE, PATCH)
- Live Built-In Endpoint Connection & Header Tester in Popup
- Custom Staging Domain Whitelist (dev.company.internal)
- 100% Local-First Privacy: Zero network telemetry, <420KB bundle
Market Differentiators
Why We Built This: Legacy Flaws vs Modern V3 Architecture
Engineered from first principles to resolve real user complaints, abandoned legacy codebases, and predatory subscription traps.
Browser Security & Isolation
Legacy extensions (Moesif, CORS Unblock) inject headers globally into every website, breaking YouTube, Netflix, and banking sessions.
Smart Localhost Safe-Mode defaults to only modifying requests originating from localhost and 127.0.0.1.
Performance & MV3 Native Engine
Intercepts requests via heavy JavaScript background proxies, causing high latency and memory bloat.
100% Manifest V3 declarativeNetRequest engine; rules executed at native browser C++ network layer with 0ms latency.
Cookie & Credential Transmission
Fails on authenticated API endpoints because Access-Control-Allow-Credentials or preflight OPTIONS headers are dropped.
Full support for credentials, authorization cookies, all HTTP verbs (POST, PUT, DELETE, PATCH), and preflight caching.
Workflow Alignment
Engineered for High-Performance Workflows
Frontend Web Developers (React, Next.js, Vue)
Full-Stack & Microservice Engineers
API Integration Specialists
Engineering Overview
Stop wasting hours debugging Cross-Origin Resource Sharing (CORS) errors during local frontend development. Fast CORS Unblocker injects standard CORS response headers into local API requests on the fly using Chromium's high-speed declarativeNetRequest engine.
Features an intelligent Localhost Safe-Mode by default: only requests originating from localhost and 127.0.0.1 have CORS headers appended. Unlike legacy tools that blindly modified all web traffic, your regular browsing, banking, and streaming sessions remain 100% secure.
Supports credentials and authentication cookies (Access-Control-Allow-Credentials: true), preflight OPTIONS caching (Access-Control-Max-Age: 86400), all HTTP methods (GET, POST, PUT, DELETE, OPTIONS, PATCH), and includes a built-in live endpoint tester.
Pricing
Start Free. Upgrade Anytime for Lifetime Power.
Instant in-app activation via Dodo Payments. Transparent lifetime license without recurring subscription traps.
Free Starter
Essential CORS unblocking for local development
What's Included:
- 10 daily toggle sessions
- Unlimited 0ms CORS unblocking on localhost & 127.0.0.1
- Full Preflight OPTIONS and Credentials support
- Live endpoint test console
- Smart Localhost Safe-Mode protection
Early Bird Pro Lifetime
Unlimited toggles & custom staging domain whitelisting for professional developers (In-App Upgrade)
What's Included:
- Unlimited daily toggle sessions & continuous unblocking
- Custom staging and remote dev domain whitelisting
- Custom HTTP request/response header injection rules
- Priority feature updates for upcoming Manifest V3 APIs
- Instant Dodo Payments license auto-activation
- Lifetime commercial license with 3-device browser sync
Install the extension for free using the store buttons at the top of the page. Pro features are activated seamlessly inside the extension.