Free Online Developer Tools — JSON, SQL & UUID
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JSON Formatter
SQL Formatter
UUID Generator
ULID Generator
Password Generator
API Key Generator
URL Encoder
UNIX Timestamp Converter
IP/CIDR Calculator
Text Diff
SVG Viewer
Color Palette
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Privacy Policy
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How to Use
Switching between five different sites for SQL formatting, JSON validation, and UUID generation gets old fast — this is a single page with the everyday tools developers reach for most.

Pick a tool from the menu to get started.
Everything runs in your browser — nothing you paste in is ever stored or sent anywhere.

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JSON Formatter
SQL Formatter
UUID Generator
ULID Generator
Password Generator
API Key Generator
URL Encoder
UNIX Timestamp Converter
IP/CIDR Calculator
Text Diff
SVG Viewer
Color Palette
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Helpful Articles
When SVG Isn't Enough — Why PNG Still Matters and How Browsers Convert Between ThemSVG's scalability and CSS flexibility don't help when platforms like OGP, email, and Slack simply reject it. Here's why PNG is still necessary and how the Canvas API handles the conversion.
Three Places Where Base64 and Base64URL Produce Different OutputThe same bytes encode differently in Base64 vs Base64URL in three distinct ways: character substitution, padding, and how = behaves in URLs. Most JWT decoding failures trace back to mixing these up.
Who Guarantees the Order of ULIDs Generated in the Same Millisecond?Plain ULID generation breaks ordering within the same millisecond. We read the monotonicFactory source to see exactly how it increments the random bits, and compare that with UUID v7.
VLSM falls apart unless you allocate uneven subnets largest firstSplitting 192.168.1.0/24 across four departments with different host counts, this post traces why allocating from the smallest subnet first leaves the address space too fragmented for later, larger blocks.
Why You Should Never Use encodeURI to Encode a Query ParameterEncoding a single query string value with encodeURI lets characters like & and = survive, which can break the structure of the URL itself. This article walks through an actual case where the URL breaks and clarifies the boundary between encodeURI and encodeURIComponent.
Why the CIDR host-count formula breaks down at /31 and /32The "-2" in the standard CIDR host-count formula comes from reserving a network and broadcast address — and that's exactly why /31 and /32 don't follow it.
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Update History
6/18/2026Added the Articles page (/articles).
5/9/2026Added the Privacy Policy page.
5/8/2026Implemented the API key generator tool.
5/7/2026Implemented the Color Palette tool. Color code comparison and Material Design gradient generation are now available.
3/20/2026Introduced SSG (Static Site Generation) to improve initial load speed and SEO.
3/10/2026Added dashboard card resizing feature.
3/9/2026Componentized the menu definitions. Changed the sidenav to a category-based accordion. Added the tool list page.
3/8/2026Implemented the Text Diff tool.
3/7/2026Implemented the URL Encode / Decode tool.
3/6/2026Improved the UI of the SVG Viewer. Renewed the app icon and brand color.
2/4/2026Added clear button to JSON Formatter, SQL Formatter, and SVG Viewer tools.
1/26/2026Implemented IP/CIDR Calculator.
1/23/2026Implemented SVG Viewer tool.
1/21/2026Implemented SQL Formatter tool.
1/20/2026Implemented Password Generator.
1/13/2026Implemented JSON formatter tool.
8/23/2025Implemented language switching functionality.
8/20/2025Implemented UUID generation.
8/16/2025Implemented the dashboard.
Contact
The full source is on GitHub, so you can see exactly how each tool works under the hood.
Found a bug or have a feature request? Open an issue and it'll get looked at.
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