Every developer has a set of tools they reach for daily — a JSON formatter when an API response is unreadable, a Base64 encoder for authentication headers, a UUID generator for database IDs. The problem is most of these tools are scattered across different websites, some require signups, and some are slow.
This guide covers the best free developer tools available online in 2025, all in one place at FileConvy.
1. JSON Formatter & Validator
The most used dev tool on the internet.
When you receive a minified JSON response from an API, it looks like this:
{"user":{"id":1,"name":"John","email":"john@example.com","roles":["admin","editor"],"active":true}}
A JSON formatter instantly makes it readable:
{
"user": {
"id": 1,
"name": "John",
"email": "john@example.com",
"roles": ["admin", "editor"],
"active": true
}
}
Our JSON Formatter does three things:
- Format — Beautify minified JSON with proper indentation
- Minify — Compress formatted JSON for production use
- Validate — Check if your JSON is valid and get the exact error location
When you need it: Debugging API responses, reading config files, preparing data for documentation.
2. Base64 Encoder & Decoder
Base64 is everywhere in web development — email attachments, JWT tokens, image data URIs, Basic Auth headers, and API credentials all use it.
Our Base64 Encoder handles both directions:
- Encode — Convert plain text or data to Base64
- Decode — Convert Base64 back to readable text
Common uses:
| Use Case | Example |
|---|---|
| Basic Auth header | Authorization: Basic dXNlcjpwYXNz |
| JWT token payload | Decode the middle section of any JWT |
| Image data URI | data:image/png;base64,... |
| API credentials | Many APIs require Base64-encoded keys |
When you need it: Any time you see a string ending in == and wonder what it says.
3. URL Encoder & Decoder
URLs can only contain certain characters. Spaces, special characters, and non-ASCII text must be percent-encoded before being placed in a URL.
Our URL Encoder converts both ways:
- Encode —
Hello World!→Hello%20World%21 - Decode —
Hello%20World%21→Hello World!
When you need it:
- Building query strings with special characters
- Debugging encoded URLs from logs
- Working with form data and GET parameters
- Handling internationalized URLs
4. Password Generator
Weak passwords are the number one cause of account breaches. A good password generator creates cryptographically random passwords that no human could guess.
Our Password Generator lets you control:
- Length — 8 to 64 characters
- Character sets — Uppercase, lowercase, numbers, symbols
- Quantity — Generate up to 20 passwords at once
- Strength indicator — Weak, Fair, Good, Strong, Very Strong
Best practices for generated passwords:
- Use at least 16 characters for service accounts
- Always include symbols for maximum entropy
- Never reuse passwords across services
- Store in a password manager like Bitwarden or 1Password
5. UUID Generator
UUIDs (Universally Unique Identifiers) are used everywhere in software — database primary keys, session tokens, file names, correlation IDs, and API request tracking.
Our UUID Generator supports:
- UUID v4 — Random, the most commonly used version
- UUID v1 — Time-based, includes MAC address and timestamp
- Bulk generation — Up to 100 UUIDs at once
Example UUID v4:
550e8400-e29b-41d4-a716-446655440000
When to use v4 vs v1:
- Use v4 for most applications — it is random and reveals no system information
- Use v1 only when you need timestamps embedded in the ID (rare)
6. Color Picker & Converter
Designers and developers constantly switch between color formats. A hex color in Figma needs to be RGB for CSS, HSL for better manipulation, or CMYK for print.
Our Color Picker converts between all formats instantly:
- HEX —
#6c63ff - RGB —
rgb(108, 99, 255) - HSL —
hsl(244, 100%, 69%) - CMYK — For print workflows
It also tells you whether the color is light or dark, and what text color to use on top of it for accessibility.
When you need it: CSS styling, design handoff, accessibility audits, theme creation.
7. HTML Formatter & Beautifier
Minified HTML from build tools or CMS systems is impossible to read. Our HTML Formatter instantly beautifies it with proper indentation.
It also works in reverse — minify your HTML to reduce page weight for production.
8. CSS Minifier
Every byte counts for page speed. Our CSS Minifier removes whitespace, comments, and redundant characters from your stylesheets.
Before:
/* Main button styles */
.button {
background-color: #6c63ff;
color: white;
padding: 12px 24px;
border-radius: 8px;
}
After:
.button{background-color:#6c63ff;color:white;padding:12px 24px;border-radius:8px}
A typical stylesheet can be reduced by 20-40% through minification.
9. JavaScript Minifier
Same concept as CSS — our JS Minifier removes whitespace, shortens variable names, and strips comments to reduce file size.
When you need it: Preparing scripts for production, reducing CDN costs, improving Core Web Vitals scores.
10. QR Code Generator
QR codes are useful for developers in more ways than just marketing — deep links, app onboarding flows, WiFi sharing, and API endpoint shortcuts all benefit from QR codes.
Our QR Code Generator supports:
- Custom colors — Match your brand
- PNG and SVG output — Vector for print, raster for web
- Error correction levels — Low (7%) to High (30%)
- Any content — URLs, text, email, phone, WiFi credentials
- Custom size — Up to 1000×1000px
Complete Developer Tools Reference
Here is a quick reference of all developer tools available on FileConvy:
| Tool | What It Does | Best For | |---|---|---| | JSON Formatter | Format, minify, validate JSON | API debugging | | Base64 Encoder | Encode/decode Base64 | Auth headers, JWT | | URL Encoder | Encode/decode URLs | Query strings | | Password Generator | Secure random passwords | Account security | | UUID Generator | v1 and v4 UUIDs | Database IDs | | Color Picker | HEX, RGB, HSL, CMYK | CSS, design | | HTML Formatter | Beautify/minify HTML | Code readability | | CSS Minifier | Minify stylesheets | Production builds | | JS Minifier | Minify JavaScript | Performance | | QR Generator | Custom QR codes | Links, marketing |
Why Use FileConvy for Developer Tools?
Most online dev tools have one or more of these problems:
- Require signup before you can use them
- Show intrusive ads or pop-ups
- Slow to load or process
- Store your data on their servers
FileConvy is different:
- No signup — Open any tool and use it immediately
- No ads — Clean interface, no distractions
- Fast — Tools respond in under a second
- Private — Nothing is stored on our servers
Bookmarking Tip
Save fileconvy.com/tools/dev as a bookmark. Every tool you need for daily development work is on that one page — no more hunting across different websites for a JSON formatter here and a UUID generator there.
All 10 developer tools are completely free. No account, no limits, no watermarks.