Every developer has a collection of browser tabs they keep returning to -- little utilities for formatting, encoding, converting, and debugging. Over the past year I've consolidated mine down to a single platform, and I want to share the tools I genuinely use on a daily or weekly basis. They all happen to live at anytools.io, they all run client-side in the browser, and none of them require an account.
This is not an exhaustive list. It is the subset I actually reach for during real work.
1. JSON Formatter & Validator
This is probably the tool I open most. Anytime I'm debugging an API response or reading a config file, I paste raw JSON in and get a clean, syntax-highlighted, collapsible tree view. It catches syntax errors instantly, which saves me from staring at a wall of text trying to find a missing comma.
When I use it: Inspecting API responses, validating config files, making nested JSON readable before sharing with teammates.
2. Base64 Encoder/Decoder
Working with auth tokens, data URIs, or encoded payloads -- Base64 shows up constantly. Instead of firing up a terminal and remembering the right flags for base64 on macOS vs. Linux, I just paste and convert.
When I use it: Decoding auth headers, encoding images for inline CSS, debugging encoded payloads in logs.
3. JWT Decoder
JWTs are everywhere in modern web apps, and being able to quickly peek at the header and payload without writing code is invaluable. This tool breaks a JWT into its three parts and displays them as readable JSON. Since it all runs in the browser, I don't worry about pasting tokens into some random website.
When I use it: Debugging authentication flows, verifying token claims and expiration times, checking which algorithm a token uses.
4. Regex Tester
Writing regex is one thing. Debugging regex is another. The regex tester lets me write a pattern, paste in test strings, and see matches highlighted in real time. It shows capture groups, explains what each part of the expression does, and flags common mistakes.
When I use it: Building validation patterns, parsing log files, writing search-and-replace patterns before running them on production data.
5. UUID Generator
Whenever I need unique IDs for test data, database seeds, or mock objects, I generate a batch of UUIDs here. It supports v4 (random) and lets you generate multiple at once.
When I use it: Seeding test databases, generating placeholder IDs for mock data, creating unique keys for configuration entries.
6. Timestamp Converter
Converting between Unix timestamps and human-readable dates is something I do more often than I'd like to admit. This tool converts both directions and supports multiple formats. It also shows "relative time" (e.g., "3 hours ago"), which is handy when digging through logs.
When I use it: Reading Unix timestamps in database records, debugging scheduled jobs, converting dates for API parameters.
7. Password Generator
For local dev environments, test accounts, and quick throwaway credentials, I use this to generate strong passwords with configurable length and character sets. It runs entirely in the browser using the Web Crypto API, so the generated passwords never touch a server.
When I use it: Setting up dev environment credentials, generating secrets for .env files, creating test user passwords.
8. Color Converter
Front-end work constantly requires jumping between HEX, RGB, HSL, and sometimes OKLCH. This tool converts between all of them and gives a live preview. I keep it open whenever I'm working on UI code.
When I use it: Converting design tokens between formats, adjusting colors for CSS, translating Figma color values to code.
9. Contrast Checker
Accessibility is not optional. The contrast checker takes two colors and tells you whether they pass WCAG AA and AAA standards for both normal and large text. I run every color combination through this before committing UI changes.
When I use it: Verifying text/background color combinations meet accessibility standards, checking hover and focus state contrast ratios.
10. URL Encoder/Decoder
Query strings with special characters, encoded redirect URIs, API parameters with spaces -- URL encoding issues are a daily occurrence. This tool handles encoding and decoding in both directions and is faster than trying to remember JavaScript's encodeURIComponent vs. encodeURI distinction.
When I use it: Debugging malformed URLs, encoding query parameters, decoding redirect URIs in OAuth flows.
11. Markdown Preview
When I'm writing README files, documentation, or blog posts (like this one), I want a live preview without spinning up a local dev server. This tool renders GitHub-flavored Markdown in real time as I type.
When I use it: Drafting README files, writing documentation, previewing markdown before committing.
12. Code Minifier
For quick one-off minification of JavaScript, CSS, or HTML snippets, this tool shrinks the code and shows you the size reduction. It is not a replacement for a proper build pipeline, but it is perfect for quick checks or inline scripts.
When I use it: Minifying inline scripts for email templates, quick size checks, compressing CSS snippets for embedded widgets.
Why These Over Alternatives?
There are hundreds of online developer tools. The reason I've settled on this particular set comes down to three things:
- They are all in one place. I have one bookmark instead of twelve. The search function finds any tool instantly.
- Client-side processing. My data stays in my browser. This matters a lot when I'm pasting JWTs, API responses, or anything that touches production data.
- No friction. No sign-up, no cookie banners, no "upgrade to pro" modals. The tools just work.
If you spend time doing any of the tasks above, give anytools.io a look. And if you have a tool you wish existed but doesn't -- I'd genuinely like to hear about it in the comments.
Top comments (0)