Free Online Tools That Never Touch Your Data
Compress images, generate QR codes, count tokens, visualize memory layouts, diagram SQL queries, and more. Everything runs in your browser — nothing is ever uploaded.
Image & Media
Image Compressor
Compress with pixel-diff preview & target size
Compress JPEG, PNG, WebP, and BMP entirely in your browser. Unique pixel-difference overlay shows exactly what changed, set a target file size, view EXIF metadata, and compare with an interactive slider.
QR Code Generator
Create, scan & batch generate — free, no watermark
Generate styled QR codes with custom dots, colors, logos, and frames. Built-in scanner verifies codes in real-time, and free batch generation lets you create dozens at once — features most tools charge for.
Text & Content
Word Counter
Words, readability, keyword density & character limits
Count words, characters, sentences, and paragraphs with readability scoring, keyword density, and built-in social media character limit checking for Twitter, Instagram, LinkedIn, Meta, and more.
Case Converter
12 formats + AP, APA, Chicago & MLA Title Case
Convert text between 12 case formats instantly. Includes style-guide-aware Title Case that properly capitalizes titles following AP, APA, Chicago, and MLA rules.
Text Cleaner
Remove duplicates, sort, regex find & replace
Remove duplicate lines, sort text, strip HTML/Markdown, and use a powerful regex find & replace with live match counting and capture group support — all in-browser.
Text Encoder
Base64, URL, HTML encoding + hash generation
Encode and decode with Base64, URL, HTML entities, and Unicode. Generate MD5, SHA-1, SHA-256, and SHA-512 hashes entirely in your browser — no server involved.
Text Diff
Word-level diff with 3 views — free, no sign-up
Compare texts with word-level inline highlighting, side-by-side view, and unified line-level diff. The kind of comparison Diffchecker charges $15/month for — yours free.
Token Counter
Count tokens for GPT & AI models + prompt builder
Count tokens using real OpenAI tokenizer algorithms with API cost estimates. Includes a prompt template builder to plan system prompts and messages within your context window budget.
Developer
Memory Layout Visualizer
Visualize struct padding & alignment for C, C++ & Rust
See exactly how compilers lay out your structs in memory. Visualize padding bytes, alignment gaps, and byte offsets for C, C++, and Rust — with optimization suggestions to reduce wasted space.
SQL Query Visualizer
Visual flow diagram for complex SQL queries
Paste any SQL query and instantly see a visual flow diagram showing tables, joins, filters, grouping, and data flow. Understand complex queries at a glance — no data leaves your browser.
MongoDB Pipeline Visualizer
Visualize aggregation stages, data flow & anti-patterns
Paste a MongoDB aggregation pipeline and see each stage as a visual flow node. Track data shape changes, detect anti-patterns like $match after $lookup, and export diagrams — all in your browser.
JSON Schema Mapper
Visual field mapping with transformation code generation
Paste two JSON structures side by side, draw visual mapping lines between fields, configure transformations, and generate JavaScript, TypeScript, Python, or jq transformation code — no data leaves your browser.
RedisJSON Path Builder
JSONPath queries with real-time results & Redis commands
Paste a JSON document, write JSONPath queries, and see matched values highlighted in real-time. Build RedisJSON commands like JSON.GET, JSON.SET, JSON.DEL with previews — all processed locally.
Why NothingLeaves?
100% Private
All processing happens in your browser. Nothing is uploaded, stored, or even seen by us. Verify it in DevTools.
Instant Results
No upload or download wait. Processing starts instantly because your data never leaves your device.
No Limits, No Catch
No hidden fees, no sign-up, no file size caps, no daily quotas. Every tool is genuinely free with no strings attached.