Focused browser tools since 2019
Sharp tools.
No fluff, no accounts.
Kobaltstack ships small browser extensions that each solve exactly one problem — no sign-ups, no tracking, no bloat.
- 6
- Tools shipped
- 100K+
- Weekly users
- 0
- Accounts required
The stack
Three tools. Zero friction.
Every card below is a production extension used daily. Click through to install.
ConverterJPG to PDF
Batch-combine images into a single PDF with page size, order, and margin controls.
Open tool
SecurityAuthenticator
Time-based 2FA codes that live in your browser — encrypted, portable, offline-first.
Open tool
ConverterMP4 to MP3
Pull clean audio out of any MP4 locally. Files never leave your machine.
Open tool
About
Do one thing. Do it exceptionally well.
We are a small independent studio shipping utility extensions since 2019. Today more than 100,000 people reach for a Kobaltstack tool every week — quietly, without ever signing up.
One job per tool
Each product answers a single question. No settings panels for things you do not need.
Your data stays local
Conversion and processing happens in your browser. Files do not touch our servers.
No account wall
Install, click, done. No logins, no email verification, no cookie popups.
Built to last
We keep shipping updates to the same tools instead of inventing new ones every quarter.
Contact
Get in touch
Have a question, partnership idea, or feedback about one of our products? We respond to every message.