Free Developer Utilities

Fast, privacy-first developer tools. All processing happens locally in your browser. No accounts required, no data sent to our servers.

ToolPad is a collection of small, focused web utilities for software engineers, DevOps practitioners, QA engineers, and security researchers. Every tool on the site solves one specific problem you run into while debugging an API response, reading a production log, reviewing a pull request, or inspecting an authentication token. You shouldn't need to install a CLI, sign up for a SaaS account, or paste sensitive data into someone else's server just to format a JSON blob or decode a JWT.

Everything runs entirely inside your browser. When you load a page, the server sends HTML, CSS, and JavaScript — and that's the end of the server's involvement. When you paste a token, a configuration file, or a piece of sample data into a tool, the computation happens on your device using standard Web APIs (JSON.parse, TextEncoder, crypto.subtle, and friends). We never see your input, we never log it, and there is no back-end code path that could. This matters when you're working with production secrets, customer data, or anything covered by a compliance regime.

Below you'll find the tools grouped into four categories: JSON and data formats, encoding and decoding, identifiers and hashes, and text and time utilities. Each tool has its own page with a clear explanation of what it does, common use cases, a frequently-asked-questions section, and links to related tools so you can chain them together when a workflow needs more than one step.

JSON Diff Tool

Compare two JSON objects side-by-side. Highlight added, removed, and changed keys instantly. Free online JSON diff tool.

UUID Generator

Generate UUIDs (v4 and v1) instantly. Bulk generation up to 500 UUIDs. Copy or download as text file.

JWT Decoder

Decode JWT tokens instantly. View header and payload as JSON. See expiration dates in human-readable format.

JSON Formatter & Validator

Format and validate JSON instantly. Pretty print with custom indentation or minify. Free online JSON formatter.

Base64 Encode Decode

Encode text to Base64 or decode Base64 to text instantly. Free online Base64 encoder and decoder tool.

Timestamp Converter

Convert Unix timestamps to human-readable dates and vice versa. Support for seconds and milliseconds. View in UTC and local time.

Regex Tester

Test regular expressions instantly. Highlight matches, view match groups, and test with flags. Free online regex tester.

URL Encode Decode

Encode or decode URL components instantly. Support for %20 and + encoding. Free online URL encoder and decoder.

Hash Generator

Generate MD5, SHA-1, and SHA-256 hashes instantly. Free online hash generator using Web Crypto API.

JSON to CSV Converter

Convert JSON arrays to CSV format instantly. Choose delimiter (comma or semicolon). Download or copy CSV output.

What's in ToolPad

JSON & Data Formats

Tools for working with JSON — the data format behind almost every modern web API. Format unreadable minified payloads, compare two versions of a config to spot drift, and convert arrays of records into CSV for spreadsheets or data warehouses.

Encoding & Decoding

Move safely between human-readable text and machine representations. Decode a Base64 blob out of an HTTP header, percent-encode a query string so it survives transport, or peek inside a JWT to see what claims a service is sending you.

Identifiers & Hashes

Generate unique IDs for database rows, event streams, or distributed systems. Produce cryptographic digests for content addressing, integrity checking, or cache keys — all using well-tested libraries and the browser's native Web Crypto API.

Text & Time Utilities

Debug a regex against sample input with instant match highlighting, or convert between Unix epoch seconds/milliseconds and human-readable timestamps when you're reading logs from a production system.

Why Use ToolPad?

Privacy by Architecture

Your data stays on your device. There is no API call that uploads your JSON, your JWT, or your regex test string to a server. This is a technical property of how the site is built, not just a promise. You can verify it in your browser's network tab.

Zero Friction

No sign-ups, no paywalls, no email-gated "premium" features. Open the tool, paste your input, and get the result. Every tool is usable within the first second of loading the page, and every action (format, decode, generate) is one click away.

Works Offline

Because every tool runs in your browser, once a page has loaded it keeps working even if your connection drops. Useful on flights, in conference Wi-Fi dead zones, or when debugging a production incident from a sketchy network.

When to Reach for Which Tool

Debugging an API response. Paste the response body into the JSON Formatter to pretty-print it and immediately spot structural issues. If the response contains a JWT in an Authorization header or in a field like access_token, drop it into the JWT Decoder to check its claims, audience, and expiration.

Reviewing a config change. Use the JSON Diff tool to compare two versions of a feature-flag file, Helm values, or Terraform output and highlight only the keys that actually changed.

Reading a production log. Logs often contain Unix epoch timestamps in seconds or milliseconds. The Timestamp Converter translates them to UTC and local time instantly. When a log entry references a content hash, verify it with the Hash Generator.

Building a quick test fixture. Generate a batch of UUIDs for seed data with the UUID Generator, then export a JSON array as CSV using the JSON-to-CSV converter for spreadsheet or warehouse import.

Writing a URL router or a log filter. The Regex Tester lets you iterate on a pattern against real sample text with live match highlighting — the fastest way to avoid shipping a broken regex.

Guides and Deep Dives

Longer-form articles on the formats and protocols behind the tools.