Top 10 Free Developer Tools You're Not Using (But Should Be)
Let's be honest — most "top tools" listicles are just ads wearing a blog post costume. This isn't that.
I've been building developer tools for years, and I'm constantly surprised by how many devs are still doing things the hard way. Copy-pasting test data from Stack Overflow. Using sketchy online converters that phone home with your data. Manually formatting JSON like it's 2008.
Here are 10 free tools that actually respect your time (and your data). Most run entirely client-side — your input never leaves your browser.
1. JSON Formatter & Validator
The problem: You're staring at a 500-line minified JSON blob from an API response, trying to find that one missing comma.
The fix: JSONFormat.co formats, validates, and prettifies JSON instantly. Paste it in, get it readable. It catches syntax errors, highlights them, and lets you collapse/expand nested objects.
Why it's underrated: Most JSON formatters are bloated or ad-infested. This one is clean, fast, and runs 100% in your browser.
2. Base64 Encoder/Decoder
The problem: You need to decode a Base64 string from a JWT, an email header, or some API payload — and you're Googling "base64 decode online" for the 400th time.
The fix: Base64Decode.co handles encoding and decoding instantly. Supports text, files, images, and URLs. No file size limits, no server uploads.
Why it's underrated: It handles edge cases that most tools choke on — UTF-8 multi-byte characters, binary data, data URIs. And it never sends your data anywhere.
3. Random IBAN Generator
The problem: You're building a fintech app, a payment form, or just writing tests — and you need valid-looking IBANs that pass checksum validation.
The fix: RandomIBAN.co generates structurally valid IBANs for 70+ countries. Each one passes the MOD-97 checksum, so your validation logic actually gets tested properly.
Why it's underrated: Most "random IBAN" generators produce garbage that fails basic validation. This one generates IBANs that are structurally correct — perfect for unit tests and staging environments.
4. Test Credit Card Number Generator
The problem: You need test card numbers for your payment integration. You know 4242424242424242, but you need Mastercard, Amex, Discover, and different BIN ranges.
The fix: Namso.io generates test credit card numbers with valid Luhn checksums across all major networks. Choose your BIN, quantity, and format — get numbers that pass frontend validation.
Why it's underrated: It's the go-to tool for QA teams testing payment flows. Supports custom BIN ranges, bulk generation, and multiple output formats.
⚠️ For testing only. These numbers are algorithmically valid but not linked to real accounts.
5. Random IMEI Generator
The problem: You're developing a mobile device management app, testing carrier APIs, or building inventory systems — and you need valid IMEI numbers.
The fix: RandomIMEI.com generates IMEI numbers with valid Luhn check digits. Pick a device manufacturer or TAC code, generate in bulk.
Why it's underrated: Finding valid test IMEIs is weirdly difficult. This tool handles the TAC database and Luhn algorithm so you don't have to.
6. Random MAC Address Generator
The problem: Network testing, device spoofing for development, populating test databases — you need MAC addresses that look real.
The fix: RandomMAC.com generates MAC addresses in any format (colon-separated, hyphenated, bare). Filter by vendor OUI, generate unicast/multicast, locally administered or globally unique.
Why it's underrated: The format options alone make it worth bookmarking. Most generators give you one format. This one gives you exactly what your system expects.
7. Hex to ASCII Converter
The problem: You're debugging network packets, reading hex dumps, or working with binary protocols — and you need to quickly convert between hex and human-readable text.
The fix: HexToASCII.co converts hex strings to ASCII and back. Handles various input formats, supports Unicode, and shows you the byte-level breakdown.
Why it's underrated: It's one of those tools you don't need until you desperately need it — and then you need it to work perfectly. This one does.
8. Lorem Ipsum Generator
The problem: Your designer needs placeholder text for mockups. Your frontend needs realistic-looking content for layout testing.
The fix: LoremIpsum.co generates paragraphs, sentences, or words of placeholder text. Classic lorem ipsum or alternative text styles.
Why it's underrated: Yes, your IDE probably has a snippet for this. But when you need 47 paragraphs of varied-length content for a CMS migration test, a dedicated tool saves time.
9. Password Generator
The problem: You need secure passwords for test accounts, CI/CD secrets, or database credentials — and you want control over length, character sets, and complexity.
The fix: Password-Generator.co creates cryptographically random passwords. Customize length, include/exclude character types, generate in bulk.
Why it's underrated: Browser password managers generate passwords, sure. But they don't let you generate 50 passwords at once with specific complexity requirements for a test suite.
10. UUID Generator
The problem: You need UUIDs for database records, API testing, or distributed system development.
The fix: CreateUUID.com generates v1, v4, and v7 UUIDs. Bulk generation, multiple formats, copy with one click.
Why it's underrated: uuidgen exists in your terminal, but this tool gives you bulk generation, version selection, and formatted output for direct paste into SQL or JSON.
The Common Thread
All of these tools share three qualities:
- Client-side processing. Your data stays in your browser. No server logs, no tracking, no "we'll store this for 30 days."
- No signup required. Open the URL, use the tool, close the tab. That's it.
- Actually maintained. These aren't abandoned side projects — they get regular updates and support modern browsers.
Bookmark the Ones You Need
You don't need all 10 today. But the next time you're Googling "random IBAN generator" or "decode base64 online," you'll wish you had this list saved.
What free developer tools are in your daily rotation? Drop them in the comments — I'm always looking for new ones to test.
Found this useful? Follow @santacruz for more developer tool deep dives and practical guides.
Top comments (1)
I never quire understand these lists or at least the wording of theses articles. Top 10 developer tools you are not using but should be. Why would I use a free IBAN generator, even tho I don't need them. The list might make sense. The wording does not!