Most developer tool roundups link to GitHub repos you have to run locally, or to SaaS products that require an account and an email confirmation before you can do anything.
Here are 16 browser-based tools on AT USE that work immediately - paste or type, get the result. Free, no registration, no install.
Encoding & Decoding
- Base64 Encoder/Decoder - Encode strings or files (including images) to Base64, or decode Base64 to text/data URI. Supports file upload up to 5 MB with live image preview.
- URL Encoder/Decoder - Percent-encode any string, or decode URL-encoded text. Useful for building query strings, debugging redirect chains, and testing API endpoints.
- HTML Entity Encoder/Decoder - Convert special characters to HTML entities and back. Both named entities (&) and numeric (&) output modes.
- Binary Translator - Convert text to binary and binary to text. Includes hex and decimal modes.
JSON & Text
- JSON Formatter/Validator - Paste JSON to format, validate, and highlight syntax errors. Shows the error line and column if malformed.
- JWT Decoder - Decode any JWT token to read header, payload, and expiry. Does not verify signatures - use for inspection, not validation.
- Text Diff - Paste two blocks of text to see a line-by-line diff. Highlights added, removed, and changed lines.
- Case Converter - Convert text between camelCase, snake_case, PascalCase, kebab-case, CONSTANT_CASE, and 8 other formats.
- Markdown to HTML - Convert Markdown (GitHub Flavored) to clean HTML. Supports tables, strikethrough, task lists. Uses marked.js; runs entirely in the browser.
- Code to Image - Screenshot any code snippet as a PNG. Choose theme, language, font size, and padding. Useful for LinkedIn posts, slides, or READMEs where you want syntax-highlighted code without a screenshot tool.
Regex, Security & Generators
- Regex Tester - Test regular expressions against sample text. Shows all matches highlighted in real time. Supports flags (global, case-insensitive, multiline, dotall).
- Hash Generator - Generate MD5, SHA-1, SHA-256, and SHA-512 hashes from any text input.
- UUID Generator - Generate UUID v4 (random), v1 (timestamp), or nil. Generate in bulk or one at a time.
- Password Generator - Generate passwords with configurable length and character sets (uppercase, lowercase, digits, symbols).
Time, Date & Scheduling
- Unix Timestamp Converter - Convert Unix timestamps to human-readable dates and vice versa. Shows UTC and local time. Works in milliseconds and seconds.
- Cron Expression Builder - Build and validate cron expressions with a visual UI. Shows the next 5 scheduled run times. Supports standard 5-field and extended 6-field (with seconds) formats.
- Timezone Converter - Convert a time between any two time zones. Supports all IANA time zones with UTC offset and DST awareness.
- Number Base Converter - Convert numbers between decimal, binary, octal, and hexadecimal.
All tools are free, server-side (for processing) or browser-side (for analysis), with files deleted after download on any tool that accepts uploads. No account, no tracking beyond standard analytics.
The full set is at at-use.com/tools/developer.
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