Free online tools
for developers
HandyTool is a lightweight toolbox. Everything runs locally in your browser—your content never leaves your device.
Private by default
Local processing, no server upload
Instant
No ads, no account required
Fast
Light deps, quick rendering
Core Tools
Pick one and get things done
Online JSON formatter, minify & validate
Beautify, compress, or check JSON syntax in your browser. No upload—your payload stays on your device.
YAML / JSON / Properties converter
Convert between YAML, JSON, and .properties locally—nothing is uploaded.
Base64 encode & decode online
Switch between plain text and Base64 for tokens, configs, and small payloads. Encodes and decodes locally in your browser.
Markdown preview (GFM) online
Write Markdown and see live rendered output with common GitHub-flavored syntax. Print-friendly. Everything stays local.
Text diff — line-by-line compare
Paste two versions, compare line by line, highlight added and removed lines, and copy a unified diff for patches or changelogs—all locally.
JavaScript regex explained in plain English
Paste a RegExp pattern and flags; get a structured Markdown breakdown of anchors, character classes, groups, and quantifiers—parsed locally.
Lorem ipsum & mock data rows
Generate filler Latin paragraphs or random sample person rows as JSON or TSV for tables and API mocks. Fictional data only; processed locally.
cURL command builder & explainer
Dissect pasted curl into method, URL, headers, and body—or build curl from a form or JSON spec with safe quoting. No server upload.
216 web-safe colors — HEX palette
Browse the classic 216-color web safe set, themed swatches, and greys. Click any swatch to copy HEX—rendered locally, nothing uploaded.
Markdown slides with themes
Turn Markdown into slides using --- page breaks, pick a theme and 16:9 or 4:3, then present fullscreen. Deck stays in your browser.
PDF merge & split (local)
Combine multiple PDFs in order, or split one PDF by every page (ZIP) or by page ranges. Runs in your browser—files are not uploaded.