Utilities
Developer tools that don't fit WhatIf Labo's finance / psychology / health "what if" simulators: formatters and validators for config and data files, plus testers and explainers for regex, globs, semver ranges, cron, subnets, and cookies. Everything runs in your browser — no Profile, no history, nothing saved.
Developer Tools
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JSON Formatter & Validator
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Pretty-print, minify, or validate JSON with a line/column error pointer.
JSON5 / JSONC Formatter & Validator
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Pretty-print JSON5/JSONC with comments kept, or minify it to strict JSON — VS Code settings.json, tsconfig.json.
XML Formatter & Validator
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Pretty-print, minify, or validate XML with a line/column error pointer — no schema/DTD validation.
YAML Formatter & Validator
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Normalize YAML indentation or convert it to JSON — no anchors, tags, or multi-document streams.
CSV Formatter & Validator
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Clean up CSV quoting or convert it to JSON — delimiter auto-detected, ragged rows flagged.
TOML Formatter & Validator
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Normalize TOML formatting or convert it to JSON — Cargo.toml, pyproject.toml, and similar.
.env (dotenv) Formatter & Validator
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Normalize .env formatting or convert it to JSON — comments preserved, duplicate keys flagged.
INI Formatter & Validator
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Normalize INI formatting or convert it to JSON — dotted [section.path] headers nest like TOML's tables.
Properties Formatter & Validator
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Normalize Java .properties formatting or convert it to JSON — real java.util.Properties syntax, dotted keys stay flat.
Markdown Front-matter Formatter & Validator
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Normalize a Markdown file's YAML front-matter block or convert it to JSON — the body below stays untouched.
Markdown Table Formatter & Validator
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Realign a GFM Markdown table's columns or convert it to JSON — a pipe inside inline code isn't split apart.
JWT Decoder
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Decode a JWT's header and payload, and check its expiry — signature is never verified.
Base64 Encoder & Decoder
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Convert text to Base64 or back, with a UTF-8-safe path and an optional URL-safe alphabet.
Unix Timestamp Converter
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Convert a Unix timestamp to ISO/UTC/local time (or back) — seconds vs milliseconds auto-detected.
URL Encoder & Decoder
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Percent-encode or decode text — component mode for query params, full mode for a complete URL.
UUID Generator & Validator
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Generate cryptographically random v4 UUIDs in bulk, or validate one and see its version/variant.
Regex Tester
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Test a JavaScript regex against sample text — highlighted matches, capture groups, live replace.
Semver Range Tester
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Test versions against an npm-style semver range — real caret/tilde/X-range and pre-release matching rules.
.gitignore / Glob Pattern Tester
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Test .gitignore patterns against sample paths — real git semantics, including the ancestor-directory gotcha.
Crontab Expression Explainer
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Plain-English description and next 5 run times for a cron expression — handles the day-of-month/day-of-week OR rule.
IPv4 / CIDR Subnet Calculator & Validator
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Network, broadcast, mask, and host range for a CIDR block, plus which IPs fall inside it — /31 and /32 handled correctly.
Set-Cookie Header Parser & Validator
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See how a browser reads each Set-Cookie header — and which ones it silently rejects, like SameSite=None without Secure.
Text Diff Checker
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Compare two texts line by line with word highlighting — and see CRLF/LF, final-newline, and trailing-space differences named.
String Inspector
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See a string's four lengths (graphemes, code points, UTF-16, UTF-8) and reveal zero-width, bidi, lookalike, and other hidden characters.
Hash Generator & Checksum Verifier
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MD5, SHA-1, SHA-256/384/512 and HMAC for text or files — and when a checksum doesn't match, it tells you why.
Number Base Converter
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Hex, binary, octal, and decimal with exact BigInt math — plus signed vs unsigned at 8/16/32/64 bits and the IDs JSON.parse would corrupt.