Developer Tools (EN)
System Prompt Formatter
Create perfectly structured system prompts for ChatGPT, Claude, and other LLMs. XML, JSON, or Markdown format with templates.
LLM API Pricing Calculator
Compare API pricing for GPT-5, Claude, Gemini, DeepSeek, Grok and 25+ models. Estimate token costs instantly.
JWT Decoder
Decode JSON Web Tokens instantly. Inspect header, payload, claims, and expiration — 100% client-side.
Regex Tester
Test and debug regular expressions in real time. Match highlighting, capture groups, and common presets.
JSON Formatter & Validator
Format, validate, beautify, and minify JSON instantly. Syntax error detection with line numbers.
Git Undo
Made a git mistake? Answer a few questions and get the exact commands to fix it. Covers wrong branch, sensitive data, bad merges, and more.
Cron Expression Generator
Build cron expressions visually. See the next run times and get a human-readable schedule description.
Data Format Converter
Convert between JSON, YAML, CSV, XML, TOML, and TSV instantly. Bidirectional, real-time, with download.
Base64 Encode / Decode
Encode and decode Base64 strings instantly. Supports standard and URL-safe Base64.
UUID Generator
Generate UUIDs (v4 random, v7 timestamp) instantly. Bulk generation, multiple formats, cryptographically secure.
CIDR / IP Subnet Calculator
Calculate IP subnets from CIDR notation. Network address, broadcast, usable hosts, binary visualization, and reference table.
Chmod Calculator
Calculate Unix file permissions visually. Convert between octal and symbolic notation instantly.
OG Meta Tag Generator
Generate Open Graph and Twitter Card meta tags with live previews for Google, Twitter, Facebook, LinkedIn, and iMessage.
Outils Freelance & Auto-Entrepreneur (FR)
Simulateur Revenu Auto-Entrepreneur
Calculez votre revenu net en auto-entrepreneur. Cotisations, ACRE, versement libératoire, IR — tout est simulé.
Simulateur TJM Freelance
Calculez votre TJM idéal en freelance. Partez de votre revenu net souhaité, l'outil calcule le tarif journalier nécessaire.
Calculateur de TVA
Calculez la TVA instantanément : convertissez HT en TTC ou TTC en HT. Tous les taux français 2026.
Finance & Investing (EN)
Compound Interest Calculator
Visualize compound interest growth with monthly contributions. Stacked bar chart, yearly breakdown, FIRE planning. 100% client-side.
Cost of Living Calculator
Compare cost of living between cities worldwide. Salary equivalent, category breakdown (rent, groceries, transport). 150+ cities indexed.
Currency Exchange Calculator
Convert currencies with live ECB rates. Compare real mid-market rate vs bank and Wise transfer fees side by side.
Health & Lifestyle (EN)
TDEE & Macro Calculator
Calculate your Total Daily Energy Expenditure and optimal macros for cutting, maintaining, or bulking. Mifflin-St Jeor formula.
Sleep Cycle Calculator
Find the best time to sleep or wake up based on 90-minute sleep cycles. Night mode for bedtime use.
Running Pace Calculator
Calculate running pace, finish time, or distance. Split tables, race predictions with Riegel formula, and common marathon pace chart.
Energy & Home
Energy Vampire Detector
Find out how much your standby devices cost you per year. Select your appliances and see the hidden electricity bill.
Calculateur Heures Creuses
Votre abonnement heures creuses est-il rentable ? Comparez tarif base vs HP/HC en fonction de votre consommation réelle.
Energy Price Increase Simulator
Simulate how energy price increases affect your bill and discover actions to offset the impact. Interactive calculator.
Why Pulsars?
Every tool runs in your browser. No server round-trips, no loading spinners.
Your data stays on your device. No accounts, no cookies, no tracking.
All tools are free to use. No premium walls, no feature gates.