Developer tools that stay in the browser
Format, inspect, and generate in this tab. No account. Labeled non-personalized ads may appear on some pages. Password and key tools stay ad-free.
- Runs in the tab
- No account
- 47 tools
- 10 languages
Favorites
0Recently Used
0Search Results
Formatters & Converters
10JSON Formatter
Validate, format, and minify JSON data.
Timestamp Converter
Convert Unix timestamps to human dates.
Color Converter
Convert HEX, RGB, and HSL colors.
Unit Converter
Convert length, weight, and more.
Config Converter
Convert between YAML, TOML, and JSON.
Text Case Converter
Convert text case (camel, snake, etc).
Code Minifier
Minify JS, CSS, and HTML code.
Image Converter
Convert and resize images locally.
SQL Formatter & Validator
Format SQL and catch common syntax issues. Supports Postgres/MySQL-friendly formatting (offline).
SVG Optimizer & Editor
Clean up and preview SVGs, then quickly adjust fill/stroke colors โ all locally.
Security & Crypto
13Password Generator
Create secure, random passwords.
SSH Key Generator
Generate Ed25519, ECDSA, and RSA SSH keys.
X.509 Certificate Inspector
Parse X.509 certificates and CSRs.
Token Cryptography Suite
Inspect, generate, and manage JWT tokens and cryptographic keys.
Encoding & Decoding Workbench
Encode, decode, hash, and identify data transformations.
SAML Inspector
Decode SAML requests and responses.
OAuth 2.0 / PKCE Debugger
Generate PKCE challenges, visualize OAuth flows, and analyze security.
Htpasswd Entry Generator
Generate apache htpasswd entries.
Log Masker
Redact PII from logs locally.
Email Security Analyzer
Understand SPF, DKIM, DMARC, routing hops, and embedded URLs from a raw email โ all locally.
Env Var Manager
Compare .env files across environments and generate a share-safe (masked) diff.
CSP Header Builder
Build a Content-Security-Policy header with clear explanations and safety checks.
Secret Scanner
Scan pasted code/config for leaked API keys, tokens, and passwords โ then generate a share-safe redaction.
Network & Web
7IP Subnet Planner
Calculate IPv4/IPv6 subnets and ranges.
Network Reference
DNS records, common ports, HTTP status codes, and protocol headers โ four references in one tabbed tool.
Bandwidth Calculator
Calculate transfer times, bandwidth needs, and TCP overhead.
Webhook Payload Inspector
Paste a captured webhook request to inspect its headers, body, and HMAC signature.
WireGuard Config Studio
Generate WireGuard configurations with local key generation and QR export.
Wireshark Filter Builder
Build Wireshark display filters and BPF capture expressions visually.
User-Agent Parser
Parse and analyze User-Agent strings.
Generators
4Utilities
13Text Diff
Compare two text files for differences.
Regex Studio
Visualize, explain, and test regular expressions with real-time diagrams.
Cron Builder
Visual cron editor with human-readable descriptions and next-run preview.
Markdown Editor
Split-pane Markdown editor with sync scroll and GFM support.
Log Viewer
Analyze large log files locally with filtering and visualization.
Curl Studio
Parse and generate curl commands.
Mermaid Studio
Live Mermaid.js diagram editor.
JSON Schema Studio
Generate JSON Schema from JSON.
Caffeinate
Keep your device screen awake using the Wake Lock API. No downloads, fully client-side.
Token Counter & Cost Estimator
Estimate token counts for GPT, Claude, and Llama families and calculate cost with your pricing.
Prompt Template Builder
Generate a clean, reusable prompt template optimized for GPT, Claude, and other chat models.
Repo Operations
Build public repository inventories, manual-stewardship records, and review descriptions in one workspace.
Pipe Mode
Chain tools together. Your data is processed in your browser, not sent to our servers.
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What runs in the tab
JSON.parse, Web Crypto, and the other browser APIs do the work. The Worker that serves the HTML does not receive the payload you paste into a tool.
Several formatter sites store pastes and expose them through predictable share URLs. In November 2025, researchers showed years of saved JSON and code from those services included cloud keys, JWTs, and internal configs. A formatter that never uploads the document has no Recent Links page to scrape.
Ads, when they appear, are labeled and non-personalized. They stay off password, SSH, Token Studio, WireGuard, certificate, secret-scanner, encoding, and pipe pages.
Eight tools people bookmark
- JSON Formatter
- Pretty-print, minify, and validate RFC 8259 JSON with line-level errors. No stored document, no share URL.
- Token Cryptography Suite
- Inspect JWT header and payload locally, generate keys, and simulate JWKS. The browser, extensions, and clipboard still see what you paste.
- Regex Studio
- Railroad diagrams and live matches so you can explain a pattern before you ship it.
- Cron Builder
- Edit a five-field crontab and see the next run times in plain language.
- Password Generator
- Draws from crypto.getRandomValues. Prefer a password manager for storage.
- SSH Key Generator
- Defaults to Ed25519, with ECDSA P-256 and RSA for older appliances. Private keys stay in the tab.
- Curl Studio
- Parse a curl command into method, URL, headers, and body, or build one from the form.
- IP Subnet Planner
- Expand IPv4 and IPv6 CIDR into network, broadcast, host range, and reverse DNS labels.
How to use it
Open a tool, paste or type, copy the result. Language and theme stay in localStorage on this device. Homepage search filters the catalog; ?q= deep-links that filter.
About, Privacy, and Terms cover the ads allow-list and edge logs. Security reports go to security@simpletool.app.