FastTools

Code Utilities & Formatting

Format, convert, and validate code, data, and developer file formats

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Code Utilities and Formatting Workflow

Every developer spends time on the same repetitive tasks: debugging malformed JSON from an API, testing a regex pattern before committing it to code, comparing two versions of a config file, or decoding a Base64-encoded token. These browser-based tools handle those tasks instantly without leaving your workflow.

JSON: Validation and Formatting

The most common JSON errors are structural: trailing commas (not valid in JSON, though valid in JavaScript), single-quoted strings (must be double-quoted), unescaped special characters, and missing colons. The JSON Formatter catches all of these and displays the error with a line number. It also minifies JSON for production use and pretty-prints for readability — both useful depending on whether you're debugging or deploying.

Regular Expressions: Test Before You Commit

Regex patterns are notoriously hard to read and easy to get wrong. The Regex Tester evaluates your pattern against test input in real time, highlights matches, shows capturing groups, and explains the pattern in plain English. Testing a complex pattern for email validation, URL extraction, or date parsing before it goes into code takes 30 seconds and prevents bugs that take hours to debug in production.

Text Comparison: Diffs and Version Changes

The Diff Checker shows exactly what changed between two text blocks — useful for comparing configuration files, reviewing API response changes, or auditing database schema migrations. The side-by-side view with green (added) and red (removed) highlighting is faster to read than scrolling through long files manually.

Encoding and Conversion Utilities

Base64 encoding is used in HTTP authentication headers, data URIs, email attachments, and JWT tokens. URL encoding is required for query parameters containing special characters. Unix timestamps appear in logs, databases, and APIs. These converters eliminate the need to write one-off scripts or look up the syntax for common encoding operations.

Frequently Asked Questions

Why does my JSON keep failing validation?

The most common JSON validation errors: trailing commas after the last item in an array or object (invalid in JSON, valid in JavaScript), single quotes instead of double quotes for strings, unescaped special characters in strings (backslash, newline, tab), and using undefined/NaN/Infinity (not valid JSON values). The JSON Formatter shows the exact line and position of the error.

What are the most useful regex patterns to know?

Email: /^[^\s@]+@[^\s@]+\.[^\s@]+$/. URL: /https?:\/\/[^\s]+/. ISO date: /\d{4}-\d{2}-\d{2}/. US phone: /^\+?1?[-.]?\(?[0-9]{3}\)?[-.]?[0-9]{3}[-.]?[0-9]{4}$/. The Regex Patterns Cheat Sheet article provides 10 copy-paste ready patterns for the most common use cases.

When should I use Base64 encoding?

Base64 is used when binary data needs to be transmitted in text-only channels: embedding images in CSS data URIs (background-image: url(data:image/png;base64,...)), sending file attachments in JSON APIs, encoding credentials in HTTP Basic Authentication headers (Authorization: Basic base64(username:password)), and storing binary data in JWT claims.

What is a Unix timestamp?

A Unix timestamp is the number of seconds (or milliseconds in many languages) elapsed since January 1, 1970, 00:00:00 UTC (the Unix epoch). It's a language-agnostic, timezone-agnostic way to represent a specific moment in time. Common in log files, database records, and API responses. The Unix Timestamp Converter shows the corresponding human-readable date in any timezone.

Why is URL encoding necessary?

URLs can only contain certain ASCII characters. Spaces, &, =, +, ?, /, and other special characters must be percent-encoded when used in query string values. For example, 'hello world' becomes 'hello%20world'. Without proper URL encoding, query parameters containing these characters will either break the URL parser or be interpreted as structural elements.