I built 109 tools that never touch a server - here is the architecture

I built 109 tools that never touch a server - here is the architecture Most "tools" sites you have used do this: You upload a file It goes to a server The server processes it You download the result Sometimes the server stores it. Sometimes it leaks. Sometimes it disappears with the company. I wanted something different. Every tool on korelyy.com runs 100% in your browser. Zero backend. Zero upload. Zero tracking. Here is the actual architecture, the real numbers after 90 days, and what I learned. What "no server" actually means For each of the 109 tools: The entire app is a static HTML + CSS + JS file It is served as-is from a CDN (Cloudflare Pages) All file processing happens in your browser via FileReader, canvas, Web Crypto API, or OffscreenCanvas Your file never leaves your device Closing the tab = the data is gone (no cookies, no localStorage, no account) This is not a marketing claim. It is verifiable: Open DevTools -> Network tab Use any tool that requires a file (image converter, JSON formatter, etc.) Reload. The only network request is for the static HTML/CSS/JS bundle. No fetch() to a server. No XHR. No upload. The file is read, processed in-memory, and downloaded. The 4 browser APIs that do 90% of the work When you remove a backend, you are left with the browser. The browser is more capable than most people think. 1. FileReader and URL.createObjectURL Read any file the user gives you: const file = document.querySelector('input[type=file]').files[0]; const url = URL.createObjectURL(file); const img = new Image(); img.onload = () => { // process image canvas.toBlob(blob => { const downloadUrl = URL.createObjectURL(blob); // trigger download }); }; img.src = url; Image conversion, PDF generation, audio trimming - all the same pattern. Read blob, process, create new blob, download. 2. crypto.subtle (Web Crypto API) Hashing, encryption, signing - all client-side: const hash = await crypto.subtle.digest('SHA-256', arrayBuffer); const hex = Array.from(new Uint8Array(hash)) .map(b => b.toString(16).padStart(2, '0')) .join(''); No need for a Node backend. The browser has FIPS-validated crypto built in. 3. canvas and OffscreenCanvas Image manipulation in 2D context: resize, crop, rotate draw shapes, text, gradients extract pixel data convert formats via canvas.toBlob() OffscreenCanvas lets you do this in a Web Worker, so the UI does not freeze on large images. 4. Worker and SharedWorker For CPU-heavy work (JSON validation, regex, large CSV parsing), offload to a Web Worker. The main thread stays responsive. The hard parts It is not all easy. Three categories of features are genuinely hard without a server: 1. Anything that needs a shared database "No server" means no central state. You cannot have user accounts, leaderboards, comments, or shared documents without a backend. My answer: I do not have those. The trade is intentional. korelyy is not a social product. It is a calculator. Calculators do not need user accounts. If you want shared state, you need a backend. Be honest about it. 2. Anything that needs to call a third-party API that requires a key Most LLM APIs, payment APIs, and OAuth flows need a server-held secret. My answer: do not call them from the client. Either skip the feature or do it via a thin serverless function. (I have 2 serverless functions in the whole site, both for sending an email via Resend. They are 30 lines total.) 3. Anything that requires lots of CPU or RAM A 4K video transcoded in the browser will lock up the UI for 30 seconds. There is no fix except "use a server." My answer: korelyy does not do video. Image, audio, text, code, JSON, PDF, CSV - all fine. Video, 3D, ML inference - skip. The SEO win no one talks about A static-only site is insanely fast for Google. Lighthouse 100/100/100/100 on every page LCP under 500ms globally TTFB under 100ms (Cloudflare edge) Total page weight under 50KB Google rewards this. My actual results after 90 days: 165 pages indexed 1,545 monthly impressions 22 monthly clicks 0 backlinks 0 marketing spend These are not impressive numbers. But the cost per impression is literally $0. And the trend is monotonically up. The 6-language "trick" Most indie sites ship English-only because i18n is painful. Mine has 6 (en, zh, es, fr, hi, ar). The trick: translations live in JSON files, not in the code. A 2,000-line tool component never knows what language it is in. The useTranslations hook from next-intl handles it. // English file { "compressImage": { "title": "Compress image" } } // Chinese file { "compressImage": { "title": "压缩图片" } } RTL (Arabic) is one CSS rule: html[dir=rtl] { ... } plus using logical properties (margin-inline-start instead of margin-left) throughout. Cost: 1 week to set up. Saved: 6x market reach with zero ongoing effort. What I would do differently After 90 days, here is what I would change: Start with SEO from day 1, not day 30. I lost 30 days of indexing time. Set up sitemap, structured data, and submit to GSC before launch. Ship fewer, better tools. I shipped 109. 20 of them are great. 60 are decent. 29 are mediocre. I would rather have shipped 30 great ones. Do not add a backend for the sake of it. Every time I was tempted to add a server, I asked "do users actually need this?" 95% of the time, the answer was no. Write the marketing page before the tool. I built tools nobody searched for. Now I check Google Trends and "People Also Ask" before building anything. When NOT to do this The no-backend approach is wrong for: Multiplayer or collaborative products Anything requiring authentication Products with ML inference Products with heavy server-side processing Anything where you need analytics For me, the trade was right. For your product, it might be wrong. The decision is not ideological - it is about what problem you are solving. Try it If you want to see the architecture in action: Image converter - upload, convert, download. Check Network tab. Zero requests. JSON formatter - paste 10MB of JSON, validates in 50ms Password generator - uses crypto.getRandomValues Markdown preview - 6 languages UI All 109 at korelyy.com/en. The whole site is open source. The architecture is not magic. It is just a willingness to say "no" to features that need a backend. Sometimes the simplest constraint is the best one.