9 tools LIVE
Developer Tools
JSON, GeoJSON, code formatters, and regex tools for developers
100% Client-Side · Zero Server Processing
Your code
never leaves
your browser.
Free, secure developer tools that process everything locally in your browser.
Popular tools
Browse all 121 tools Free Forever
No Sign-up
WCAG 2.1 AA
Instant Results
121+
Tools Available
0ms
Data sent to servers
19+
Languages Supported
100%
Free, Always
What is CodeLint.Dev?
Free online tools that respect your privacy
CodeLint.Dev is a free suite of 120+ tools for developers, finance professionals, and anyone working with AI. Format and validate JSON, decode JWTs, generate QR codes and passwords, calculate loans and taxes, count LLM tokens, and much more — all from one fast, ad-light site with no account required.
What sets it apart is privacy: every tool runs entirely inside your browser using JavaScript. The data you paste, type, or upload is never sent to a server, never logged, and never shared. Most tools even keep working offline once the page has loaded. Learn more about how it works and who builds it.
Read about CodeLint.Dev Built for every kind of user
One toolkit, every use case
Software Developers
Regex, JWT, Base64, UUID, hash tools and 50+ more dev utilities — all run offline in your browser, no sign-up.
Explore developer toolsFinance & Business
Mortgage, EMI, SIP, tax estimator, IBAN/SWIFT validator and 30+ FinTech calculators — private, no account needed.
Explore finance toolsEveryone
QR code generator, unit converter, password manager, color picker and 20+ everyday tools — works in 19 languages, no sign-up.
Explore everyday toolsEverything you need.
Nothing you don't.
17 tool groups, 121 tools — technical, fintech, AI & more. Each one runs entirely in your browser.
10 tools LIVE
Encoders & Converters
Encode, decode, and convert data between formats
6 tools LIVE
Generators & Utilities
Handy generators and converters for everyday developer tasks
5 tools LIVE
Date, Time & Clocks
Timers, countdowns, and stopwatches for everyday time tracking
2 tools LIVE
Barcode & QR
Generate barcodes and QR codes for any data
13 tools LIVE
Media & Audio
Browser-based audio and media tools for musicians and developers
15 tools LIVE
Reference & Data
Country codes, flags, and reference tables for developers
4 tools LIVE
Network & Security
IP lookup, HTTP header analysis, SSL certificate decoder, and CIDR subnet calculator for sysadmins and DevOps
Currency, forex & crypto — live.
Live rates fetched directly in your browser. No proxies, no stored data.
4 tools LIVE
Currency & Forex
Live currency conversion, exchange rate tracking, and crypto tools — all client-side
6 tools LIVE
Loan & Credit
EMI calculators, mortgage tools, interest calculators, and debt planning — all client-side
6 tools LIVE
Investment & Returns
SIP, CAGR, ROI, stock profit/loss, dividend yield, and portfolio allocation — all client-side
6 tools LIVE
Personal Finance
Budget planner, net worth, retirement, emergency fund, expense ratio, and tip calculator — all client-side
6 tools LIVE
Business & Accounting
Invoice generator, markup calculator, break-even, cash flow, depreciation, and runway tools — all client-side
5 tools LIVE
Payment & Validation
Credit card validator, BIN lookup, IBAN formatter, UPI validator, and payment fee comparator — all client-side
6 tools LIVE
Tax & Compliance
Income tax estimator, capital gains, GST/VAT calculator, tax bracket lookup, IBAN and SWIFT/BIC tools — all client-side
Prompt, model & token tools.
All local, all free.
8 interactive tools and 10 reference pages for LLM developers — prompt builders, token counters, cost calculators and more.
8 tools LIVE
AI Tools
Compare LLMs, count tokens, build prompts, and explore AI/ML concepts — all client-side, no API keys required
10 tools LIVE
AI Reference
In-depth reference guides for LLM tokenization, optimization, sampling, benchmarks, embeddings, and safety
Your data never
leaves your device.
Zero data transmission
Every tool runs as pure JavaScript in your browser. No API calls, no WebSockets, no telemetry on your input data.
Instant, offline-capable
Processing happens at native browser speed — no round-trip latency. Works without internet once the page has loaded.
Open and auditable
All logic is client-side JavaScript. Use your browser's DevTools to verify that nothing leaves your machine.