Built by one developer, for developers.

Why this site exists

Search for something like “base64 encoder” and you land on a page carrying four ad slots, a cookie wall, a newsletter modal, and a tool that posts your input to a server you know nothing about. You wanted to convert eleven characters. It took nine seconds and three dismissals.

Tessacode Tools is the version of that page I wanted to exist. Every tool here does one thing, appears already focused, and finishes before you have finished reading the heading. There is no account, no dashboard, and no modal.

Nothing is uploaded. Genuinely.

This is the part worth being precise about, because every tool site claims it and few mean it. Every tool on this site is implemented with browser APIs: TextEncoder and btoa for Base64, crypto.subtle for hashing and JWT signature verification, Intl.DateTimeFormat for timezone maths. The parsers for JSON, YAML, Markdown, cron, and CSS are hand-written and run in the same tab you are reading this in.

There is no backend to send anything to. The whole site is static HTML on a CDN, so there is no server-side code that could receive your data even if it wanted to. Open your browser's Network tab, paste a production API token into the JWT decoder, and watch nothing happen. That is the entire pitch.

The practical upshot: pasting a secret, an internal config file, or a customer payload into these tools is safe in a way that a server-side converter never can be.

How each tool is built

Every tool's logic lives in a plain TypeScript module with no framework dependencies, which keeps it testable and keeps the shipped bundle small. A few choices worth calling out, because they are where the tools differ from the alternatives:

• The JSON validator reports line and column. Browsers throw wildly different messages for the same broken document and none reliably give a position, so the parser is hand-written to point at the exact character and name the cause.


• The cron parser implements the OR rule correctly. When both day-of-month and day-of-week are restricted, cron fires if either matches. Most parsers get this backwards.


• The Markdown converter escapes by default. Raw HTML in the source renders as visible text rather than live markup, so output you paste elsewhere can never carry a payload.


• The YAML converter follows the 1.2 core schema. So no stays the string "no" instead of turning into false — the Norway problem.


• The CSS minifier walks characters, not regexes. Which is why data URIs, quoted content strings, and calc() spacing survive intact.

Who builds it

Tessacode Tools is made by Tessacode Solutions, a one-person studio building small, fast web software. The tools are a side project that exists because I kept needing them and kept disliking the options.

If something is wrong, slow, or missing, I would genuinely like to know. The fastest way to improve a tool is someone telling me the case it fails on. Get in touch.

How the site pays for itself

Hosting is free and the domain costs about fifteen dollars a year, so the bar is low. The plan is display advertising, kept to placements that do not cover the tool or shift the page while it loads. If the ads ever make a tool worse to use, they are the thing that goes.

No tool will be moved behind a paywall. If a paid tier ever appears it will be for genuinely additional things such as API access or bulk processing, and everything available today will stay free. What you see now is the free tier, permanently.

The ads and the analytics are also the only reason this site touches your data at all, which the privacy policy covers in specific detail.