FastTools

Number & Code Converters

Convert binary, hex, Roman numerals, data formats, and numeric codes for developers and everyday use

10 tools

Tools in This Collection

Number and Code Conversion Workflow

Number and code conversions come up in two main contexts: computer science and development work, and everyday text or reference situations. These tools cover both.

For developer work, number base conversions are fundamental. Decimal 255 = binary 11111111 = hexadecimal FF. Decimal 42 = binary 101010 = hex 2A. The Binary Converter handles all four bases (binary, decimal, hex, octal) in both directions with instant conversion. The Hex Color Converter translates between CSS hex codes (#3B82F6), RGB (59, 130, 246), and HSL (217°, 91%, 60%) — essential when moving values between design tools and code.

Data format conversions are frequent in API development and configuration management. The CSV to JSON Converter transforms spreadsheet exports into JSON arrays for API ingestion — paste a CSV with headers and get a properly structured JSON array with one object per row. The YAML to JSON Converter handles configuration file formats (Kubernetes YAML, GitHub Actions, Docker Compose) to JSON. The TOML to JSON Converter converts Rust/Cargo and Python/Poetry config files.

For reference and text work, the Roman Numeral Converter handles both directions — useful for clock faces, chapter numbering, movie release years (MMXXVI = 2026), and legal documents. The Number to Words Converter spells out numbers for check writing and formal documents (1,250,000 = one million two hundred fifty thousand). The Morse Code Converter translates between text and dots/dashes. The Paint Color Code Converter translates between paint manufacturer codes for matching colors across brands.

Frequently Asked Questions

How do I convert a decimal number to binary?

Divide the number by 2 repeatedly and record the remainders from bottom to top. For example, 13 ÷ 2 = 6 R1, 6 ÷ 2 = 3 R0, 3 ÷ 2 = 1 R1, 1 ÷ 2 = 0 R1 — reading remainders bottom to top gives binary 1101. The Binary Converter does this instantly for any number in any base.

What's the difference between a hex color code and RGB?

Hex color codes (#3B82F6) are just a compact way to write RGB values in hexadecimal. The hex digits pair up: 3B = 59 red, 82 = 130 green, F6 = 246 blue. Both systems describe the same color — hex is more common in CSS and HTML, RGB is common in design software and canvas APIs. The Hex Color Converter handles all conversions including HSL.

When should I use CSV to JSON vs YAML to JSON conversion?

Use CSV to JSON when converting spreadsheet data or database exports to structured JSON arrays — each row becomes an object with the column headers as keys. Use YAML to JSON when working with configuration files (Kubernetes manifests, GitHub Actions workflows, Docker Compose files) that need to be parsed by tools expecting JSON. Both converters run entirely in your browser with no data uploaded.