UD5 Toolkit
PDF Merger - Online Combine Multiple PDFs into One
Combine multiple PDF files into a single document. Drag and drop to reorder pages. All merging is done locally for confidentiality.
PDF Compressor - Online Reduce File Size Locally
PDF Compressor
Reduce PDF file size directly in your browser. 100% private – no upload needed.
Local ProcessingDrag & Drop PDF Here
or click to browse
Frequently Asked Questions
It uses powerful JavaScript libraries (like pdf-lib) to process and optimize your PDF directly in your browser. The file never leaves your device – no upload to any server.
Absolutely. All processing happens in your browser's memory. No data is ever transmitted, stored, or collected. Your privacy is fully protected.
There is no fixed limit. It depends on your device's available memory. Even very large PDFs (hundreds of MB) can be processed, though they may take a little longer.
No, our local compression focuses on removing redundant data, unused objects, and optimizing file structure. Text and images remain untouched, so there's no visible quality loss.
Local compression gives you better privacy (no upload), instant processing (no slow network transfers), and no file size restrictions. It's safer and often faster.
Currently, the tool processes one file at a time for optimal performance. You can easily compress multiple files sequentially.
All modern browsers: Chrome, Firefox, Safari, Edge, and Opera. They all support the required JavaScript features for local processing.
Only to load the tool initially. Once the page is open, the compression engine runs offline – no further internet connection is required.
Yes, it's 100% free. No hidden costs, no watermarks, no registration required. Enjoy unlimited local compression.
We remove unused objects, streamline metadata, and use efficient object streams. This reduces file size without altering your content's appearance.
Image Compression Visualizer - Online Before/After Slider
Drag a slider to compare your original image with a compressed version (e.g., WebP). See the quality difference and file size savings.
Compression Streams API Demo - Online Gzip/Deflate Raw
Compress and decompress text using the browser's native Compression Streams API. See the binary output size.
HTML Class Name Shortener – Online Reduce File Size
Replace long CSS class names with short random strings. Map generated. For production optimization.
Online PDF Page Counter - Instant Document Inspector
Check how many pages a PDF has without uploading it (uses FileReader). Also shows file size and title if available. Simple and fast client-side tool.
GIF Playback Speed Changer - Online Slow Down or Speed Up
Load an animated GIF and adjust its frame delay to make it slower or faster. Download the modified GIF. All local.
Brotli Compression Level Tester - Online Optimal Setting
Compress text with Brotli at different quality levels. See size reduction and time. Find the sweet spot for your static assets.
Font Tech & Format Checker - Online Supports incremental font?
Detect browser support for font‑tech() and font‑format() values in @font‑face src. Check COLRv1, variable, etc.
Online Video Trimmer - Cut & Save Clips Locally
Set start and end times for a video and trim it without re-encoding. Download the clip. Pure browser.
Base64 Encoder & Decoder - Online Base64 Converter
Convert text and files to Base64 or decode Base64 back to original content. Processed locally with no server upload, ensuring complete data security.
File MIME Type & Magic Bytes Detector - Online
Drop a file to see its MIME type and the first few magic bytes (hex and ASCII). No upload, works instantly.
Big‑O Complexity Visualizer - Online Compare O(1) to O(n!)
Plot different Big‑O complexities on a chart. See how O(log n) stays flat while O(2^n) explodes. Educational reference.
File Type from Magic Bytes Detector - Online Identify Unknown Files
Drop a file and see its detected type based on the first bytes (magic number). Identifies hundreds of formats. Local.
File Extension Database Lookup - Online Search Type
Search for any file extension to see its full name, MIME type, and description. Covers thousands of entries. Static data.
Base32 Encoder & Decoder - Online Base32 Converter
Encode or decode text using Base32 scheme. Ideal for legacy systems and data obfuscation. Works completely offline in your browser for maximum security.
SVG Transform Merger - Online Combine Transforms
Take an SVG element with multiple transform attributes and merge them into a single matrix. Simplify your SVG code locally.
prefers‑reduced‑motion Tester - Online A11y Check
Simulate reduced motion preference and test your animations. Copy the media query snippet. Keep your users safe.
Online Spell Checker - Free Text Correction with Suggestions
Check English spelling and get suggestions using the browser's built-in dictionary. Highlight errors instantly. No data leaves your machine.
Data Structure Visualizer - Online Array, Stack, Queue
Add, remove, push, pop items and watch the data structure change visually. Supports arrays, stacks, and queues. For CS students.
Sorting Algorithms Visualizer - Online Bubble, Quick & Merge
Watch classic sorting algorithms step through a randomized bar chart. Adjust speed and array size. Great for learning algorithm efficiency.
Picture‑in‑Picture Tester - Online Float Video Anywhere
Open a test video in Picture‑in‑Picture mode. Control entering and leaving PiP. Copy the code snippet for your own app.
transform‑style: preserve‑3d Tester - Online 3D Nesting
Nest elements in 3D space with preserve‑3d vs flat. Rotate the parent and see children behave differently.
Image Format MIME Checker - Online Identify True Type
Drop an image that might have wrong extension and see its real format (JPEG, PNG, WebP) based on header bytes.
Photo Mosaic Generator - Online Tile a Big Picture from Small
Upload a main image and a folder of tile images, and the tool creates a photomosaic. Rendered in canvas. All local.
Auto‑Fill vs Auto‑Fit Visualizer - Online CSS Grid
Resize the container and see the difference between repeat(auto‑fill, …) and auto‑fit. Understand responsive grid behavior.
Local Font Viewer & Preview - Online Test Styles
Browse the fonts installed on your system and type a custom phrase to see how it looks. Uses Local Font Access API where available.
Logical Sizing Properties Demo - Online block‑size & inline‑size
Compare width/height with block‑size/inline‑size in different writing modes. Understand intrinsic sizing. Copy best practices.
Email Header Parser - Online Analyze Email Delivery Path
Paste raw email headers and get a human-readable breakdown of the delivery route, authentication results, and delays. Private analysis.
3rd‑Party Script Impact Analyzer - Online See Cost
Enter a URL and see a waterfall of external scripts with their download size and execution time estimate. Identify performance culprits.
MIME Type ↔ Extension Lookup - Online Quick Reference
Search by MIME or file extension to see the corresponding type. Helpful when configuring web servers. Static.