# LocalTools

## Summary

LocalTools is a collection of **privacy-oriented, browser-based utilities**: formatting, conversion, generators, PDF and image helpers, crypto/PKI helpers, and developer workflows. **Tool data is intended to be processed locally in your browser**—your pasted text, files, and images are **not uploaded to LocalTools’ servers for processing**. The site is built as a **lightweight Next.js + React** app with **client-side logic** and selective **Web Workers** for heavier tasks.

**Localization:** The site is **English-only**. UI strings live in **`src/lib/english.ts`** (generated site copy). Routes are flat: **`/{englishSlug}`** (e.g. `/json-formatter`), plus `/`, `/all-tools`, `/learn` (guides with internal links to tools), `/privacy`.

## Tools

- **Learn (guides)** — Short articles at `/learn` (Markdown in-repo) with internal links to tools; same privacy story as the utilities.
- **JSON Formatter & Validator** — Beautify, minify, and validate JSON entirely in the browser.
- **JSON ↔ YAML converter** — Convert between JSON and YAML in-browser using `js-yaml`; parse errors show line/column when available.
- **JSON to TypeScript** — Paste JSON and generate `interface` / `type` declarations from one sample (merged array shapes, optional fields, primitive unions); configurable root name and `export`; local-only.
- **JSON Minifier** — Validate then `JSON.stringify` to one line; copy or download `minified.json`; parse errors before output; separate UX from the formatter/beautify tool.
- **JSONPath evaluator** — `JSON.parse` in-tab; `jsonpath-plus` (safe eval) for queries; pretty JSON output, optional path+value list; local only.
- **XML formatter** — `DOMParser` (`application/xml`) validates; pretty-print (2/4 spaces) or minify via local serializer; copy or download `formatted.xml`; local only.
- **TOML formatter & validator** — `@iarna/toml` parses TOML with row/column errors; `stringify` for formatted output; copy or download `formatted.toml`; local only.
- **.env file editor** — Parse dotenv-style lines in-browser; validate keys and duplicates; normalize quoting; merge two blocks (overlay or base wins); optional sort keys; copy or download `.env`; no `${VAR}` expansion.
- **INI / Java properties ↔ JSON** — Parse INI (`[sections]`, `key=value`, `;`/`#` comments) or Java `.properties` (comments, `\` line continuations, `=`/`:`) to JSON; reverse to INI (scalar-only nesting as sections) or dot-key `.properties`; pure TypeScript in-tab.
- **CSV to JSON / HTML / Markdown** — Parse CSV with detected delimiters and export to JSON, HTML tables, or Markdown locally.
- **URL Encoder & Decoder** — Percent-encode/decode with component vs full-URI rules and parse full URLs into parts.
- **HTML Entities** — Escape and unescape HTML entities for safe snippets and attributes.
- **Hex Encoder & Decoder** — Convert text to UTF-8 hex and decode flexible hex dumps back to text.
- **UUID Generator** — Generate RFC 4122 v4 UUIDs, nil UUID, and batches locally via Web Crypto.
- **ULID Generator** — Generate sortable ULIDs and decode embedded timestamps and randomness.
- **NanoID Generator** — Generate compact URL-friendly IDs with presets, custom alphabets, length control, and batches.
- **Random String Generator** — Generate CSPRNG passwords/tokens with charset controls, ambiguity options, and batches.
- **MIME Type Lookup** — Search a bundled extension ↔ MIME reference table with filters and copy actions; fully offline.
- **Unix timestamp converter** — Parse Unix epoch integers (seconds vs milliseconds with Auto or forced mode), fractional seconds, or date strings; show ISO UTC, locale local/UTC, and both epoch scales with copy; `Date` range limits apply; local only.
- **Timezone converter** — Compare IANA zones for one reference instant (local datetime picker or “Now”); offsets, abbreviations, and formatted local times via `Intl`; full zone list when `supportedValuesOf('timeZone')` exists; tab-separated row copy; local only.
- **Date difference calculator** — Two local datetime pickers (start/end); signed ms and seconds; exact day/hour/minute/second breakdown from |Δ| ms; calendar years/months/days in local wall time; decimal day/hour/week totals; ISO UTC for each side; swap and Now; local only.
- **ISO 8601 parser** — Paste ISO calendar, week (YYYY-Www-D), ordinal (YYYY-DDD), or basic compact strings; field breakdown, normalized UTC ISO, Unix seconds/ms; Z and ±offset; example chips and Now; strict patterns with Date.parse fallback note; local only.
- **TOTP Tool** — Generate a Base32 TOTP secret, show an otpauth QR for authenticator apps, live codes, and verify codes with Web Crypto locally.
- **AES-GCM Encrypt & Decrypt** — Paste hex AES key and IV, optional AAD; encrypt or decrypt text or files with Web Crypto AES-GCM (128-bit tag); outputs Base64 or hex, all local.
- **RSA Key Generator** — Generate 2048–4096-bit RSA keypairs in-browser (RSA-OAEP, RSASSA-PKCS1-v1_5, RSA-PSS with SHA-256); export PKCS#8 private and SPKI public PEM locally via Web Crypto.
- **PEM Decoder** — Parse one or more PEM blocks locally: BEGIN/END labels, joined Base64 payload, DER byte length, short hex preview; optional header lines (e.g. Proc-Type) skipped; copy actions.
- **HKDF & PBKDF2 Playground** — Derive key bytes with Web Crypto: PBKDF2 (passphrase, salt, iterations, SHA-256/384/512 or SHA-1) or HKDF (IKM, salt, info); UTF-8 or hex inputs; copy hex/Base64; parameter summary for debugging.
- **JWT Debugger** — Encode (HMAC) and decode JWTs with browser-side crypto; secrets stay on the device.
- **SVG to JSX** — Optimize SVG with SVGO in a worker, then emit JSX/TSX or optimized SVG.
- **Image Optimizer** — Compress, resize, and convert images (e.g. PNG/JPG/WebP) using canvas APIs in-browser.
- **Secret Share** — Seal text with AES-GCM; share a link where ciphertext lives in the URL hash (fragment not sent to server on request).
- **PDF Toolkit** — Merge, split, and trim PDFs with in-memory processing (e.g. pdf-lib), no uploads.
- **Cron Generator** — Build and validate cron expressions with human-readable explanations and next run times.
- **CSS Unit Converter & Fluid Type** — Convert CSS units, build `clamp()` fluid type, and convert colors (HEX/RGB/HSL).
- **Color converter** — Sync HEX, RGB, HSL, and OKLCH with a live swatch, opacity slider, and per-format copy; OKLab math in-browser.
- **WCAG contrast checker** — Pair foreground and background colors for WCAG 2.x contrast ratio with AA/AAA pass levels (normal, large, UI); live preview and sample pairs; local sRGB luminance math.
- **CSS box-shadow generator** — Stack shadow layers (offset, blur, spread, rgba color, inset); live card preview on light/dark/checker; copy full `box-shadow` declaration; local only.
- **QR Code Studio** — Generate QR codes (URL, text, Wi‑Fi, vCard) and scan from image or camera locally.
- **Browser Auditor** — Inspect fingerprinting-related browser signals and estimate a local privacy score (WebRTC/STUN nuance applies).
- **Code Snap Studio** — Turn code into syntax-highlighted images (e.g. Shiki) for sharing, exported locally.
- **Diff Checker** — Compare two texts at character, word, or line granularity with side-by-side or inline views.
- **Text Statistics** — Word, character, line, paragraph, and rough sentence counts with configurable words-per-minute reading-time estimate; plain-text summary copy; all local.
- **Text Case Converter** — camelCase, PascalCase, snake_case, kebab-case, and CONSTANT_CASE from pasted phrases with local tokenization (spaces, separators, camelCase breaks); **Input shape** whole box vs per-line; per-variant and batch copy; offline.
- **Slugify** — URL/file slugs in-browser: Unicode vs Latin ASCII (accents dropped, small ligature map), hyphen or underscore, whole text or one slug per non-empty line; copy output; local only.
- **Sort Lines** — Sort lines A→Z or Z→A (`localeCompare`, optional numeric digit ordering and case rules), reverse order without sorting, or shuffle with `crypto.getRandomValues`; preserves trailing newline when present; copy output; local only.
- **Dedupe Lines** — Drop duplicate rows from pasted text: keep first occurrence in list order, or output sorted unique lines with `localeCompare` and optional numeric digit ordering; case-sensitive or case-insensitive line keys; occurrence counts; trailing newline preserved; local only.
- **Find & Replace (batch)** — Multiline literal or JavaScript-regex find/replace in-browser; literal mode escapes metacharacters and keeps replacement dollars literal; regex mode with g/i/m/s/u flags and normal `$1`/`$&` substitution; live match counts; local only.
- **Lorem Ipsum Generator** — Paragraphs with random sentence counts, exact word-count filler, or bullet lists from an extended pseudo-Latin vocabulary; optional classic opening; bounds for words-per-sentence; **Regenerate** uses `crypto.getRandomValues`; copy; local only.
- **Whitespace Normalizer** — LF vs CRLF output, expand tabs to fixed column stops or leading spaces to tabs, strip trailing spaces/tabs per line, preserve trailing newline when present; live per-line stats; local only.
- **Levenshtein distance** — Minimal insert/delete/substitute edit count between two strings (UTF-16 code units); optional DP matrix when both strings are short; distance-only for longer inputs; local only.
- **Subnet Calculator** — IPv4/IPv6 subnet math, CIDR, masks, usable ranges, binary view, and classification hints.
- **Password Strength & Entropy** — Analyze passwords with entropy estimates and zxcvbn-backed guidance locally.
- **Multi-Hash & Base64 Factory** — Base64/hex/URL/HTML encodings plus SHA-256/512/SHA-1/MD5 and local file checksums.
- **Markdown Studio** — Live GitHub-flavored Markdown editing with preview, export, and local persistence (e.g. local storage).
- **RegEx Studio** — Test regex with live highlighting, explanations, cheat sheet, and code snippets (worker-backed matching).
- **SQL Formatter Studio** — Format/minify SQL for common dialects and build `CREATE TABLE` scripts from a visual schema UI.
- **Web Font & Typography Workbench** — Pair fonts, modular scales, variable axes, fallback overlay, and export CSS/HTML snippets.
- **Cloud Resource Cost Estimator** — Compare illustrative AWS/Azure/GCP-style compute and storage costs using bundled manifests and local FX math.
- **PKI & Certificate Studio** — Generate RSA/ECC keys, CSRs, self-signed certs, and inspect PEM chains locally (Web Crypto / PKI.js).
- **HMAC & Webhook Verifier** — Compute and verify HMAC signatures for raw webhook bodies with hex/Base64 and provider-style headers.