Best Free Online Developer Tools in 2026: Regex, Base64, JSON & More

September 5, 2026 · 5 min read

Every developer has a set of go-to tools for quick tasks that do not justify opening an IDE or writing a script. Testing a regex pattern, decoding a Base64 string, formatting JSON for readability, generating a secure password — browser-based tools handle these in seconds without context-switching from your workflow.

Regex Testing

Write and test regular expressions with real-time highlighting of matches. See capture groups, test replacement patterns, and debug complex expressions visually. Much faster than testing regex inside your code — you see the results immediately as you modify the pattern.

Base64 Encoding and Decoding

Encode strings to Base64 for API payloads, data URIs, and JWT inspection. Decode Base64 strings to see their contents. Essential for debugging authentication tokens, email headers, and encoded data in API responses.

JSON Formatting

Paste minified or messy JSON and get clean, indented, readable output. Validate JSON structure, find syntax errors, and compare JSON objects. Converting between JSON and other formats (YAML, XML) is also a common need.

Password and Key Generation

Generate cryptographically secure passwords for accounts, API keys for applications, and random strings for tokens. Set length, character requirements, and format. Never generate security credentials manually when a proper generator is available — human-chosen randomness is not random.

Try It Now

Our free Regex Tester handles this instantly — no signup, no limits.

Also useful: our Base64 Encoder for related calculations.