100% Client-Side • Zero Telemetry • 80+ Utilities

Private Developer Tools for Modern Engineers

Professional formatters, encoders, cryptography suites, SQL visualizers, and calculators. Every tool processes data strictly inside your browser. No server calls, no telemetry, no tracking.

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100% Local Only

Showing 82 tools

Local

JSON Formatter & Validator

Format, beautify, validate, and minify JSON with interactive collapsible tree explorer, line-number error markers, and JSON5 relaxed syntax support.

developer

Local

YAML Formatter & Validator

Format and validate YAML streams with multi-document support (---), tab indentation warning fixers, block/flow formatting, and YAML to JSON conversion.

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Base64 Encoder & Decoder

Encode and decode UTF-8 Unicode text, files, images, and Data URLs with URL-safe Base64 toggles, line wrapping, and live image preview thumbnails.

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JWT Decoder & Inspector

Base64URL decode JWT tokens, inspect registered and custom claims (exp, iat, iss, sub), detect security vulnerabilities, and verify HMAC signatures.

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UUID Generator & Validator

Generate v4 random, v7 time-ordered sortable, and v1 timestamp UUIDs with bulk generation up to 5,000 items, custom formatting, and structural validation.

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Cron Expression Tester & Debugger

Validate, debug, and simulate cron schedules with field-by-field error diagnostics, upcoming execution timelines, moment checkers, and DST edge-case alerts.

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Local

Unix Timestamp Converter

Convert between Unix epoch timestamps and human dates with auto-unit detection (s, ms, μs, ns), live ticking clock, multi-timezone comparisons, and date math.

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Regex Tester & Debugger

Live regex tester with all JS flags (g, i, m, s, u, y), dual-layer match highlighting, capture group inspectors, substitution replace, and cheat sheets.

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Local

SQL Formatter & Beautifier

Format and beautify SQL across PostgreSQL, MySQL, T-SQL, SQLite, BigQuery, Snowflake, and Oracle with customizable casing, comma style, and minify mode.

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Markdown Editor & Studio

Full-featured Markdown editor with live split preview, GFM tables, KaTeX LaTeX math, Mermaid diagrams, syntax highlighting, and PDF export.

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Neural Network Visualizer & ML Studio

Interactive client-side machine learning playground. Draw shapes or digits on canvas, train an MLP in real time, and visualize live synaptic weights, activations, and loss curves.

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Local

Password & Passphrase Generator

Generate cryptographically secure passwords and Diceware passphrases with Shannon entropy metrics, custom symbol sets, batch generation, and auto-clearing clipboard.

security

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Engineered for Speed, Privacy, and Reliability

Why thousands of developers and privacy-conscious users bookmark Toolzy.

Zero Server Logs

All crypto key generation, AES ciphering, and JSON formatting execute 100% in your browser using standard Web Cryptography and V8 engines. No external API calls.

Sub-Millisecond Execution

Eliminate network latency. Transforms and syntax validations run immediately with zero round-trip overhead, even when working offline.

Modular & Self-Contained

Every single utility can be used embedded in the Toolzy suite or opened standalone with zero external dependencies for distraction-free workflows.