Free Developer Tools — Code Faster, Ship Cleaner
Format JSON, encode Base64, generate QR codes and passwords, decode JWTs and more — all in your browser with zero installs and zero data leaving your machine.
All Developer Tools
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By Vizo ToolLast updated August 20263 min read
Developer Tools: Everything in One Place
Every developer has a browser tab full of scattered tools for the same five jobs: formatting JSON, encoding strings, generating IDs, designing CSS and decoding tokens. Vizo Tool collects them all in one fast, private place.
Better still — the HTML/CSS/JS and SQL playgrounds let you write and run real code without leaving the site. No accounts, no uploads, no telemetry.
Why Use Developer Tools?
Free, private and built for real workflows.
Private by Default
Sensitive data like passwords, JWTs and SQL stays in your browser — it never hits a server.
Instant Results
Real-time formatting, validation and generation with zero page reloads and zero latency.
No Installs Needed
No npm packages, no CLI setup, no extensions. Every tool works in any modern browser.
Live Playgrounds
Run HTML/CSS/JS with a live preview and console, or execute SQLite queries with sql.js — fully client-side.
What’s Inside
Every tool ships with the essentials and then some.
JSON Formatter & Validator
Beautify, minify and validate JSON with a tree view and precise error line numbers.
Base64 Encoder / Decoder
Encode and decode text, files and images to and from Base64 with copy and download.
QR Code Generator
QR codes for URLs, WiFi, WhatsApp, UPI and more — with colors, logos and PNG/SVG/PDF export.
Password & UUID Generators
Cryptographically strong passwords with a strength meter, and UUID v1/v4/v7 in bulk.
CSS Generators
Design gradients and box shadows visually with live preview and one-click CSS copy.
JWT Decoder & SQL Formatter
Decode JWT headers, payloads and expiry, and beautify SQL with syntax highlighting.
How to Use Developer Tools
A simple, repeatable workflow.
Open the tool
Choose JSON, Base64, QR, password, UUID, CSS, JWT, SQL — or a full playground.
Paste or generate your input
Drop in code, text or a URL. Most tools validate and format as you type.
Copy or export
Copy the result to your clipboard, download a file, or keep iterating in the live playground.
Common Use Cases
- Beautifying minified API responses before debugging
- Encoding images as data URLs for inline assets
- Generating WiFi and payment QR codes for print
- Creating strong, unique passwords for every account
- Inspecting JWT tokens during auth debugging
Best Practices
- Never paste production secrets — the tools are private, but your clipboard isn't your friend.
- Use the tree view on large JSON to navigate nested data instead of scrolling.
- Pick UUID v7 for time-ordered database keys, v4 for random identifiers.
Common Mistakes to Avoid
Small habits that save you time and frustration.
Treating Base64 as encryption — it's encoding and is trivially reversible.
Reusing the same password generator settings for master passwords.
Generating QR codes without a quiet zone, then finding they don't scan.
Related Tool Categories
More free tools, right around the corner.
Frequently Asked Questions
Everything you want to know about developer tools.
Are the developer tools really free?
Yes — every developer tool is free, unlimited and requires no sign-up.
Does the JSON formatter validate as I type?
Yes — it validates in real time and shows the exact error with a line number for fast fixes.
Can the QR generator encode WiFi networks?
Yes — enter the network name and password to generate a scannable WiFi QR code.
Are my passwords and tokens stored anywhere?
No. Everything is generated and processed locally in your browser — nothing is transmitted or saved.
What can the SQL playground do?
It runs real SQLite in the browser with sql.js — create tables, query sample databases, import CSV and export results.
Is the HTML/CSS/JS playground like CodePen?
Very similar — split editors for HTML, CSS and JS with a live preview, console, templates and ZIP export.
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