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100% Client-Side Sandboxed Security

TetraBrain Desk — 59 Free Local Browser Tools

TetraBrain Desk is a privacy-first toolbox of 59 browser-based utilities for structured data (JSON, CSV, YAML, XML), text processing, security (JWT, HMAC, hash), media (QR, images, PDF), conversions (units, timezones, colors), and encoding. All tools run entirely in your browser using WebAssembly and native APIs — no data ever leaves your device, no accounts required, no server-side processing. Features include JSON formatting & validation, JWT decoding & verification, QR code scanning via camera, image compression & PDF conversion, timezone conversion, and more. Works offline after first visit. Open source, ad-free, tracking-free.

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JSON FormatterText Diff CheckerBase64 Text EncoderBase64 UTF-8 DecoderRFC 3986-Style URI Component EncoderHTML Formatter with Preview
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Focused subcategories surface the right tools without forcing you through the entire catalog.

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Processing

Minify or key-sort JSON and move between nested documents and dot-path flat records while preserving JSON value types.

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JSON MinifierJSON Minifier parses valid JSON and serializes the same data without formatting whitespace; malformed JSON is rejected before output. Essential for reducing payload sizes in API responses, optimizing network transfers, and preparing compact configuration files for production deployments.Structured Data / ProcessingTry it
JSON SorterJSON Sorter parses valid JSON and orders object keys according to the selected mode while retaining array order and data values. Useful for normalizing API responses, creating deterministic outputs for hashing, and preparing JSON for stable version control diffs.Structured Data / ProcessingTry it
JSON FlattenerJSON Flattener converts nested object and array paths into flat keys using the workspace's documented path notation while retaining the corresponding values. Useful for flattening hierarchical data for CSV export, database imports, spreadsheet analysis, and simplifying deeply nested API responses.Structured Data / ProcessingTry it
JSON UnflattenerJSON Unflattener rebuilds nested objects and arrays from path-like keys and reports invalid input instead of silently guessing at malformed JSON. Useful for reversing flat key-value exports, reconstructing hierarchical data from spreadsheet imports, and restoring structured JSON from dot-notation paths.Structured Data / ProcessingTry it

Conversion

Convert JSON records into CSV, XML, or YAML while making array, nesting, scalar, and escaping behavior explicit.

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JSON to CSVJSON to CSV converts compatible JSON records into delimited rows using the columns and delimiter selected in the workspace. Essential for analysts exporting API data to spreadsheets, preparing data for import into databases, and creating reports from JSON data sources.Structured Data / ConversionTry it
JSON to XMLJSON to XML maps parsed JSON objects and arrays into XML elements using the selected root and conversion options. Useful for developers integrating between JSON APIs and XML-based systems, migrating data formats, and generating XML documents from structured data.Structured Data / ConversionTry it
JSON to YAMLJSON to YAML serializes parsed JSON values as YAML text; downstream consumers should still verify scalar quoting and schema expectations. Essential for generating Kubernetes manifests, Docker Compose files, and configuration files from JSON data sources.Structured Data / ConversionTry it

Validators

Test regular expressions and check URL or email syntax with visible match, parsing, and failure details.

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Regex TesterRegex Tester compiles JavaScript regular expressions with the selected flags and highlights matches and capture groups against the supplied sample text. Essential for developers building, debugging, and validating regular expressions for data extraction, input validation, and text transformation.Code & Web / ValidatorsTry it
URL ValidatorURL Validator parses the entered string with the workspace's URL rules and reports syntax components; it does not request or verify the destination. Essential for developers validating user-submitted links, auditing URL formats, and catching malformed addresses before processing.Code & Web / ValidatorsTry it
Email ValidatorScreen one trimmed address with the workspace's simple pattern: non-space text, one @ separator, a dot in the domain portion, and at least two trailing non-space characters. Useful for form validation, data cleanup, and quick sanity checks before sending. Note: this is syntax checking only, not mailbox existence verification.Code & Web / ValidatorsTry it

Image Transformer

Compress browser-supported images or arrange selected images into a PDF document without uploading source files.

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Image to PDF and Image Extension ConverterConvert up to 20 PNG, JPEG, WebP, or SVG files into resized PNG/JPEG/WebP downloads or an ordered A4, Letter, or Legal PDF entirely in the browser. Perfect for creating multi-page documents from screenshots, generating print-ready layouts, and preparing image collections for sharing or archiving.Media & Files / Image TransformerTry it
Image Compressor and Dimension ResizerProcess up to 20 PNG, JPEG, or WebP images locally with Canvas, optional 400-3000 px bounds, and browser JPEG/WebP quality from 10% to 100%. Ideal for web developers, content creators, and anyone reducing file sizes before upload without losing control over quality settings. All processing stays in the browser.Media & Files / Image TransformerTry it

Cryptography

Calculate MD5 or SHA digests and decode JWT header and payload claims without presenting decoded data as verified trust.

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Hash GeneratorGenerate standards-compatible MD5 plus Web Crypto SHA-1, SHA-256, and SHA-512 hexadecimal digests from UTF-8 text entirely in your browser. Useful for verifying file integrity, creating fingerprint identifiers, password storage research, and data deduplication. MD5 is included for legacy compatibility only.Security & Identity / CryptographyTry it
JWT DecoderParse a three-segment JSON Web Token into UTF-8 JSON header and payload objects, inspect registered/custom claims and timing, and view signature bytes without verifying trust. Essential for developers debugging authentication flows, inspecting token contents, and diagnosing expiry or audience mismatches locally.Security & Identity / CryptographyTry it

Transform

Change letter case or sort text lines with explicit ordering and duplicate behavior for lists, labels, and editorial data.

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Text Case ConverterConvert text locally to uppercase, lowercase, title case, or camelCase with the exact JavaScript and Unicode-aware rules implemented by this workspace. Essential for developers normalizing identifiers, content writers formatting headings, and anyone cleaning up inconsistent text casing. Handles edge cases like apostrophes and hyphens correctly.Text & Content / TransformTry it
Text SorterText Sorter splits the supplied text into lines and applies the selected alphabetical, numeric, length, or shuffle operation to that list. Useful for organizing data exports, ranking items, cleaning up log output, and preparing ordered lists for presentation or analysis.Text & Content / TransformTry it

Recommended Multi-Step Pipelines

API Payload Review

Turn a captured JSON response into a readable document, then compare its serialized fields with a known reference payload.

JSON FormatterText Diff Checker
Local Web Asset Preparation

Compress browser-ready images, assemble approved visuals into a PDF, and translate selected sRGB colors into implementation values.

Image Compressor and Dimension ResizerImage to PDF and Image Extension ConverterHEX, RGB and HSL Color Converter

Private by architecture

Your files and input stay in browser memory. Tools run locally without upload APIs or private processing servers.