About

The problem

Developers use dozens of small tools every day: format a JSON response, decode a JWT, convert a timestamp, check a regex, hash a string. Each task takes seconds, but finding a tool that works means searching, clicking, waiting — and often pasting sensitive data into a website you have never heard of.

The alternatives are worse. Desktop tools need installation and updates. Cloud tools need an account, an API key, and a connection. And AI tools — which many people now reach for first — require you to describe what you want, wait for a response, and trust that the answer is correct. For a task that takes five seconds locally, that is a bad trade.

The idea

Tresna is a collection of small, fast, private developer tools that run entirely in your browser. No server, no account, no tracking, no data collection. You open a tool, paste your input, and get the answer immediately.

The constraint is the feature. Because there is no server, there is nowhere for your data to go. That is not a policy promise — it is an architectural fact. The site could not transmit your input if it wanted to.

What makes it different

• Private by architecture, not by promise. Your input never leaves your browser. There is no server that could receive it, no database that could store it, no log that could leak it.
• Fast by design. No waiting for a server response, no API rate limits, no queue. The tools run on your machine, at the speed of JavaScript.
• Deterministic. The same input always produces the same output. There is no model to hallucinate, no randomness in the result, no “that depends”.
• Works with sensitive data. API keys, tokens, credentials, logs with personal data — you can use these tools with data you would never paste into a chat window.
• No usage limits. No “you have reached your daily quota”. Use the tools as much as you need.
• Free, forever. No subscription, no premium tier, no “upgrade to unlock”. The tools are free because they cost nothing to run.

What it is not

• Not a replacement for a real IDE. These are small utilities for quick tasks, not a development environment.
• Not a code generator. The tools format, decode, convert and inspect. They do not write code for you.
• Not a cloud service. There is no backend, no sync, no collaboration. Everything is local.
• Not a startup. This is a tool, not a product roadmap. It exists because it is useful, not because it will raise funding.

The stack

Built with Next.js, exported as static files. The site is a folder of HTML, CSS and JavaScript that any static host can serve. The tools are written in TypeScript, tested with Vitest and Playwright, and run entirely in the browser.

The only runtime dependency is a YAML parser, used by the YAML converter. Everything else is hand-written. The result is a site that loads fast, works offline, and makes no third-party requests.

The name

Tresna is a word that means “three” in Basque. It refers to the three ideas the project is built on: fast, private, and free. Three constraints that shape every decision.

Contact

Questions, feedback, or suggestions? See the contact page.