Free Developer Tools
Formatting, validating, and converting data is part of every developer workflow. These tools run entirely in your browser: paste or upload a file, get a result instantly, and rest assured that nothing is sent to a server or logged.
The rack
JSON Formatter & Validator Stable Format and validate JSON with readable indentation, precise error messages, and byte-size stats — fully local. JSON Minifier Stable Compress JSON to its smallest valid form — strip all whitespace, count the bytes saved, and copy or download. CSV to JSON Converter Stable Convert CSV files and pasted tables into JSON objects with automatic delimiter detection and header mapping. JSON to CSV Converter Stable Convert a JSON array of objects into RFC 4180 CSV with correct quoting, column union, and copy or download. Base64 Encoder & Decoder Stable Encode text or files to Base64 and decode back, with UTF-8 handling, validation, and size stats — fully local. AI Token Counter Stable Estimate tokens and API cost for any prompt across GPT-4o, Claude Sonnet 4, and other models — fully local. Regex Tester Stable Test regular expressions live against your own text with match highlighting, capture groups, and flags — fully local. Text Diff Checker Stable Compare two blocks of text line by line with added, removed, and unchanged highlighting plus change statistics — fully local. Unix Timestamp Converter Stable Convert between Unix seconds, Unix milliseconds, ISO 8601, and human-readable local time — live, fully local. UUID Generator Stable Generate RFC 4122 version-4 UUIDs from cryptographically secure randomness — one at a time or in bulk, fully local.
About this category
Developer Tools on Toolivaro follow the same standard as every other page on the site: each tool shows its formula or method, its assumptions, a worked example, and its limitations, and every result is computed locally in your browser.
All tools are reviewed on a regular schedule. If a calculation looks wrong to you, use the correction link at the bottom of the tool page — corrections are reviewed by a human and the reviewed date is updated when changes land.
Other categories
Business Calculators Profit margin, markup, break-even, and cash runway calculators that help you make fast, accurate business decisions. Home & Construction Estimators Paint, flooring, tile, concrete, and gravel estimators with metric and imperial units, waste allowances, and package counts. Time & Date Tools Date differences, business days, time-zone conversions, and meeting-overlap planning with correct daylight-saving handling. Image Tools Resize, compress, and convert JPG, PNG, and WebP images privately — processing happens locally, and your files are never uploaded. All tools Browse the complete Toolivaro catalog.