I Built 20+ Privacy-First Browser Tools That Never Upload Your Data (All Single-File)

Every "free online tool" I tried had the same catch: your file gets uploaded to somebody's server before anything happens. CSV with customer emails? Uploaded. Invoice PDF? Uploaded. Password list? You'd have to be brave.

So I went the other direction. I've spent the past few months building a collection of single-file HTML tools — each one is literally one .html file. You open it in your browser and everything runs locally with JavaScript. Nothing ever leaves your machine. No accounts, no server, no tracking, no "free tier" limits.

All 30+ of them are collected here (free online versions, no signup): goodyuanbo.github.io

Here's what's in the toolbox, grouped by what people actually ask me for:

📊 Data & CSV work

• DropBoard — drag in a CSV, get a filterable dashboard with charts in seconds. This is the flagship. The free Lite version covers most day-to-day stuff.
• Page2CSV — paste a table from any webpage, get clean CSV back. No more copy-paste into Excel and fixing the mess.
• FinPack — 7 personal finance calculators: loan amortization, compound interest, FIRE number, mortgage comparison.

📄 Docs & writing

• MarkForge — Markdown editor with live preview, exports clean HTML/PDF.
• CleanSlate — strips tracking pixels, weird fonts and formatting junk from pasted text.
• TimeLedger — project time tracking that exports timesheets as CSV.
• SRT Studio — fix, shift and clean up subtitle files without uploading your video project anywhere.
• ChapterForge — turns timestamps into YouTube chapters.

🔐 Privacy & compliance

• PassForge — generates strong passwords locally (crypto API, offline).
• A11yCheck — quick accessibility checklist auditor for HTML pages.
• PrivacyForge — drafts privacy-policy pages from simple answers.
• SubLens — audits cookie banners and tracking scripts on a page you paste in.

🛠 Dev utilities

• CronWhisper — explains cron expressions in plain English (and builds them visually).
• JWTLens — decodes and validates JWT tokens, shows header/payload/expiry.
• ReqForge — builds HTTP requests with headers/auth, generates cURL/Python/JS snippets.
• RagSplit — splits long documents into RAG-friendly chunks with overlap control.
• QRForge — offline QR generator (custom-built encoder, no external libs).

🎨 Creator tools

• ThumbForge — resizes/frames images for YouTube thumbnails and social cards.
• BioLink — a single-file "link in bio" page you can host anywhere.
• MailSig — generates clean HTML email signatures.

💸 Money & job hunt

• TaxNap — quick US federal tax estimator (2026 brackets).
• RunwayCalc — startup runway and burn-rate calculator.
• MeetingCost — live ticker of what a meeting costs while it runs.
• LateFee — invoice late-fee and interest calculator.
• ATSMatch — paste a job description + your resume, get a keyword match report.

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Why single-file? Because you can download any of these, put the .html file on a USB stick, and it will still work in 10 years. No dependencies, no build step, no npm install, no "this service has been discontinued". It's the anti-SaaS.

Everything is usable free in the browser: goodyuanbo.github.io

If you want the downloadable offline versions (plus extras like batch mode and dark mode in some tools), they're on my store — and there's a bundle with everything at ~50% off: the complete toolkit

Happy to answer questions in the comments — and if you have an idea for a tool that should exist (especially "I wish I could do X without uploading my file somewhere"), tell me. That's basically my roadmap now.