Security2026-08-237 min read
JWT Structure & Claims: Anatomy of a JSON Web Token (RFC 7519)
Deep dive into JSON Web Token (JWT) architecture: RFC 7519 structure, registered vs custom claims, Base64URL encoding, and signature verification mechanics.
Developer-First Web Utilities
Privacy-first browser tools for modern work.
Share files over direct P2P connections, save encrypted code snippets, format data structures, and test coding fluency—entirely inside your browser tab with zero tracking.
P2P WebRTC Encrypted•Zero Account Sign-ups•Client-Side Execution
Paste Sandbox
paste.cosharex.com
// Zero-Knowledge sharing
import { encrypt } from "./crypto";
const payload = "Confidential token";
export default () => encrypt(payload);
Client EncryptedAES Protected
File Share App
file.cosharex.com
Encrypted WebRTC Stream
peer-d93a.cosharex.local
dataset_prod_v2.tar.gz78% (64 MB/s)
Direct Connection0 Bytes Stored
Live JSON Sandbox
formatter.cosharex.cominput.json8 lines • Local
Client-Side EngineOpen 23-in-1 Suite
Core Products
Single-purpose developer tools, running entirely in your browser.
CoShareX gives you immediate, account-free web utilities that execute on your local machine. Launch any tool in a dedicated tab with zero setup.
Direct P2P
File Share
Send files directly between devices over encrypted WebRTC peer connections. Transfers stream directly without cloud storage limits, intermediary servers, or file size caps.
WebRTC P2PDirect TransferNo Size Caps
Paste Share
Share formatted markdown documents, logs, and code snippets. Text encrypts in your browser before saving, with decryption keys kept solely in the URL hash fragment.
Markdown EditorSyntax HighlightingAuto Expiry
WASM Engine
Online LaTeX Compiler & Resume Builder
Write and compile LaTeX documents directly in your browser with zero setup using WebAssembly, or craft ATS-friendly resumes from proven Harvard-style templates with instant local PDF generation.
WebAssembly TeXATS Resume TemplatesClient-Side PDF
Formatter Suite
An offline-ready developer workspace to validate JSON syntax, prettify code dialects, convert data formats, and run encoding utilities directly on your machine.
23 Developer ToolsJSON & SQLLocal Processing
Vector Generator
QR Generator
Design, customize, and export high-resolution vector QR codes for URLs, WiFi networks, contact vCards, and SMS prompts with custom colors and logo embedding.
SVG & PNG ExportWiFi & vCardCustom Colors
Tool Registry
Formatter & Converter Suite (23 Utilities)
Every utility operates via Web Workers or native browser APIs. Zero cloud roundtrips for your sensitive payloads.
Encoding & Security
Base64 Encoder / Decoder
Encode and decode plain text or binary data locally
Cryptographic Hash Generator
Compute SHA-256, SHA-512, and MD5 message digests
JWT Decoder
Inspect JSON Web Token headers, payloads, and timestamps
URL Encoder / Decoder
Escape or unescape URI query parameters and percent characters
Password Generator
Generate cryptographically secure passwords in your browser
Code Formatters & Utilities
SQL Formatter
Pretty-print SQL queries for Postgres, MySQL, and SQLite
HTML / CSS / JS Formatters
Indent markup and clean frontend source files
UUID v4 Generator
Generate random RFC 4122 v4 unique identifiers
Regex Tester
Test regular expressions with real-time match group highlighting
Unix Timestamp Converter
Convert epoch seconds and milliseconds to readable dates
Security Architecture
Built for security-minded developers who value privacy.
Traditional web tools upload your sensitive tokens, proprietary code, and large binary files to multi-tenant databases. CoShareX reverses this paradigm with pure client-side execution.
Local Machine Execution
Code formatting, JSON validation, and file parsing run in your browser via dedicated Web Workers. Raw inputs never touch a remote backend.
Zero-Account Architecture
No logins, email confirmations, or tracking cookies. Every tool is immediately ready to execute without friction.
Direct Peer-to-Peer WebRTC
Files stream directly from browser to browser using encrypted WebRTC data channels, bypassing cloud storage limits and middleman servers.
Zero-Knowledge URL Hash Keys
Pastes and notes encrypt locally with WebCrypto. Encryption keys live exclusively in the URL hash fragment (#), which browsers never send to servers.
Browser Isolation Architecture
Non-Custodial1File Sharing TransportP2P SCTP
Browser A ↔ STUN/TURN Handshake ↔ Browser B (Encrypted Stream)
2Paste CryptographyAES-GCM-256
Key derived locally → stored in URL #hash → server receives ciphertext only
3Formatter ThreadingWeb Workers
Multi-MB payloads chunked in worker threads → UI main thread locked at 0ms
Verified Zero Analytics TelemetryRFC 8831 / WebCrypto
Interactive Map
The CoShareX Unified Ecosystem
Hover over the nodes below to visualize how different privacy utilities share the same local-first web sandbox.
Dev Arcade
Sharpen Your Developer Typing Speed & Symbol Reflexes
Test your raw coding throughput, bracket muscle memory, and symbol accuracy on real JavaScript, Python, and SQL snippets directly in your browser.
Engineering Blog
Technical articles & protocol deep dives
Explore RFC standards breakdowns, WebRTC transport architectures, client-side cryptographic models, and data formatting benchmarks.
Architecture2026-08-248 min read
UUID vs GUID vs ULID vs NanoID: Choosing the Right Identifier in 2026
Compare modern unique identifiers: UUID v4 vs Microsoft GUID vs ULID vs NanoID vs UUID v7. Entropy, sortability, database B-Tree clustering, and URL safety.
SecurityJuly 23, 202610 min read
Why Client-Side Web Crypto is Replacing Databases for Web Utilities
Learn why storing user files and text logs on centralized SQL server databases is a legacy risk, and how client-side Web Cryptography API sandboxing ensures privacy.
FAQ
Frequently Asked Questions
Clear answers explaining our local-first browser operations and decentralized protocols.
Ready for faster, account-free developer tools?
Launch any tool instantly in your browser tab. Zero onboarding friction, zero data profiling, and immediate local execution.