LanguageFree online converter & developer tools
ToolMill is a fast, privacy-first toolbox that runs entirely in your browser — no uploads, no accounts.
Everything you do stays on your device. Your input is processed locally client-side, so you can safely work with sensitive text like tokens, headers, config snippets, and logs.
All tools are fully functional offline once the site is cached on your device (for example after a first visit, or after installing as a PWA). Offline support is available when you need it.
Start with these popular utilities:
Popular tools
Jump into the most-used utilities — fast, private, and copy-friendly.
Unix Timestamp and Epoch Converter
Convert Unix timestamps and epoch seconds into readable dates, or turn human time back into epoch values for logs, APIs, databases, analytics events, and debugging. It is especially useful when working across backend systems, JavaScript dates, and monitoring tools. ToolMill performs the conversion instantly in your browser so you can inspect time values without exposing internal timestamps to another service.
Development
Password Generator — Strong Random Passwords
Generate strong random passwords instantly in your browser. Choose length and optional character sets (uppercase, lowercase, numbers, symbols) to create secure passwords for accounts, Wi‑Fi, API keys, and apps. Uses cryptographically secure randomness when available. Runs 100% locally — nothing you type is sent to a server — and works offline after installing ToolMill as a PWA.
Security
JSON Pretty Print, Minify, and Validate
Format JSON for readability, minify it for compact storage, and validate it before using it in APIs, config files, frontend apps, or test fixtures. This tool is useful when debugging payloads, comparing responses, cleaning copied JSON, or shrinking data for transport and logging. ToolMill processes everything in your browser, making it a fast privacy-friendly option for working with sensitive JSON.
Data
JSON Validator
Validate JSON and get precise, line-by-line error messages. Use it to catch subtle issues like trailing commas, comments, unescaped characters, and malformed numbers before shipping configs or API payloads. Runs entirely in your browser for privacy and can work offline when installed as a PWA.
Data
Base64 Encode / Decode Tool
Encode text into Base64 or decode Base64 back into readable content directly in your browser. It is useful for inspecting tokens, debugging authorization headers, checking config values, decoding API payloads, and converting plain text without using a remote service. ToolMill runs fully client-side for privacy and continues to work offline after installation.
Encoding
URL Encode / Decode (Percent-Encoding)
URL Encode/Decode (percent-encoding) converts unsafe characters into a URL-safe format and back again. Use it for query strings, redirect URLs, UTM parameters, and debugging API requests (RFC 3986). Runs 100% locally in your browser — no uploads — and works offline after installing ToolMill as a PWA.
Encoding
Privacy-first tools — no uploads
ToolMill runs client-side in your browser. We do not collect, store, or transmit what you paste into the tools — including security-sensitive data like tokens, API keys, passwords, and logs.
What you can do with ToolMill
ToolMill is a collection of small, focused utilities for everyday developer and productivity tasks — designed to be fast, copy-friendly, and safe for sensitive text.
- Encode/decode text (Base64, URL encoding)
- Format & validate structured data (JSON)
- Convert timestamps and units (Unix epoch time)
- Generate strong passwords and secrets
How it works
Pick a tool, paste your input, and copy the result. All tools work offline once the site is cached on your device (including after installing as a PWA).
Common use cases
- Decode Base64 strings from headers, tokens, and config values
- Pretty-print and validate JSON payloads and API responses
- URL encode/decode query parameters safely
- Convert Unix epoch timestamps to human time (and back)
Who it's for
Developers, QA, SRE/DevOps, analysts, students — anyone who needs quick conversions without opening heavyweight software.
FAQ
Do you upload my data?
No. ToolMill runs in your browser. We don’t send your input to a server for these tools.
Can I use ToolMill offline?
Yes. Install ToolMill as a PWA and all tools work offline (after the first load).
Is ToolMill free?
Yes — free to use. We reserve ad space to keep the site running.
Browse all tools
Looking for something else? Explore every utility by category, or see the full list.
Categories
Browse tools by category — quick utilities for everyday tasks like encoding, formatting data, generating secrets, and converting timestamps.
Data
JSON, YAML, and CSV conversions and validation.
Encoding
Base64, URL encoding, HTML entities, hex, and ROT13.
Security
Passwords, passphrases, UUIDs, and random strings — generated locally.
Text
Trim, dedupe, and transform text casing for clean copy/paste.
Development
Developer utilities for timestamps, query strings, APIs, debugging, and web workflows.
Financial
Offline financial-format helpers like card-number validation and check-digit verification.