Every developer has a list of "quick task" sites they visit ten times a week.
Compress a PDF. Format some JSON. Generate a UUID. Decode a Base64 string.
The problem: most of these sites make you create an account, upload your file
to their server, or click through three ad pages before you get a result.
I got tired of it, so I built ToolVerse —
browser-based tools that process everything locally where possible. No account.
No file upload. No redirects.
Here are the five I use most:
1. JSON Formatter & Validator
toolverseapp.com/tools/json-formatter
Paste minified or broken JSON, click Format, get readable indented output with
validation errors highlighted. Runs entirely in the browser — nothing is sent
anywhere.
I use this constantly when inspecting API responses from curl or Postman that
come back as a single compressed line.
2. UUID Generator
toolverseapp.com/tools/uuid-generator
Click once, get a UUID v4. Uses crypto.randomUUID() under the hood — no
server round trip, no account, instant copy.
Useful for: test fixtures, mock API payloads, seeding a staging database,
or any time you need a realistic-looking identifier without connecting to a
real database.
3. Base64 Encoder / Decoder
toolverseapp.com/tools/base64-encoder-decoder
Toggle between encode and decode, paste your value, click Convert. Completely
local.
The use case I hit most: API docs that show an encoded sample and I need to
inspect the structure before deciding how to handle it in code.
4. PDF Compressor
toolverseapp.com/tools/pdf-compressor
This one runs in the browser using pdf-lib. Select
your PDF, click Compress, download a lighter copy. No upload to a server.
The technical limitation: browser-side PDF compression mainly removes
redundant objects and optimizes structure. Photo-heavy scans won't shrink as
much as text documents. But for the 95% use case (a doc that's slightly too
big to email), it works.
5. PDF Merger
toolverseapp.com/tools/pdf-merger
Also built on pdf-lib. Select multiple PDFs, set the order, download a merged
file. Nothing leaves your browser.
This is the tool I built first because the alternatives all either charged for
it or uploaded your files to a cloud service. For most document bundles — a
cover letter + resume + certificates — there's no reason to involve a server.
What's the stack?
- Framework: Next.js 16 App Router, TypeScript
- PDF processing: pdf-lib
- Image processing: Browser Canvas API
- QR codes: qrcode
-
AI tools: OpenAI API (
gpt-4o-mini) with a mock fallback for local dev - Hosting: Vercel
The whole thing is on GitHub: github.com/LazSpace/ToolVerse
What browser-based tools do you keep bookmarked? I'm building more —
happy to hear what's missing.