How I Built a 100% Local, Privacy-First Tool Suite Using WebAssembly

Sikandar — Mon, 09 Nov 2026 12:11:27 +0000

As developers, we know the golden rule of data privacy: never send user data to a server if you don’t have to.

Yet, the internet is flooded with "free" online converters and AI tools that require you to upload your files to unknown servers. I got tired of this trade-off, so I built PrivateTools — a suite of 47+ utilities that process everything 100% locally in the browser.

Here is a look at 5 of our newest tools and the tech behind them:

1. Local AI Audio Transcriber

Instead of relying on cloud APIs, this tool runs OpenAI’s Whisper model directly in the browser using @xenova/transformers and WebAssembly. Users can transcribe confidential meetings or lectures with zero network requests.

🔗 Try it: Local AI Audio Transcriber

2. PDF Splitter by Exact Size

Built with pdf-lib, this tool solves a specific pain point: strict government/job portal upload limits (e.g., "max 200KB"). It iteratively adjusts compression to hit the exact byte target client-side.

🔗 Try it: PDF Splitter by Exact Size

3. VCF to CSV/Excel Converter

Parsing messy iPhone/Android contact dumps usually requires uploading personal data. This tool uses vanilla JavaScript regex to cleanly map .vcf blocks into structured CSV format locally.

🔗 Try it: VCF to CSV Converter

4. FLAC to MP3 Converter

Powered by FFmpeg.wasm, this handles high-resolution audio conversion entirely in the browser’s memory, bypassing the 50MB upload limits of typical cloud converters.

🔗 Try it: FLAC to MP3 Converter

5. Video Compressor for Discord (8MB)

A pure WebAssembly utility that compresses videos to exactly 8MB (or 25MB) for Discord uploads, preventing the dreaded "File is too powerful" error without uploading to sketchy third-party sites.

🔗 Try it: Discord Video Compressor

The Tech Stack: Next.js, Tailwind CSS, FFmpeg.wasm, and Transformers.js.

The entire project is open-source. If you’re building local-first apps or have ideas for new privacy-focused utilities, I’d love to hear your feedback!