Process CSV, JSON, and PDF files, test regex patterns—all in your browser. No uploads, no servers, no tracking. Your data stays on your device.
Select a tool below and start processing your files immediately. No learning curve, no configuration required.
Clean, merge, and transform CSV files with precision. Handle thousands of rows instantly with duplicate removal, data normalization, and powerful find & replace.
Format, validate, and debug JSON data with syntax highlighting. Instantly beautify minified API responses and pinpoint errors with precise line numbers.
Test and debug regular expressions with live matching. Get pattern explanations, access a library of common patterns, and generate code for JavaScript, Python, Go, and Java.
Merge, split, compress, and organize PDF files directly in your browser. Reorder pages, rotate, and extract—all without uploading your files to any server.
Decode and debug JSON Web Tokens privately. View header and payload claims, validate expiration, and generate parsing code for multiple languages.
Format, validate, and convert YAML files. Perfect for Kubernetes configs, Docker Compose files, and GitHub Actions workflows.
Build and understand cron expressions with a visual builder. Preview execution times and get human-readable explanations.
Three simple steps to process your files. No account needed, no software to install.
Drag and drop files or click to browse. Your files stay on your device—nothing is uploaded.
Select the transformations you need: merge, dedupe, format, validate, or convert.
Get your processed files instantly. All transformations happen in your browser.
Unlike most online tools that upload your files to remote servers, Toolkernel processes everything locally in your browser. Your sensitive data—customer lists, API keys, financial reports—stays on your computer. We can't see it, we don't store it, and it never travels over the internet. Verify this yourself by watching your browser's network tab while you work.
Most online tools upload your files to their servers. We take a fundamentally different approach.
Your files are processed entirely in your browser using WebAssembly and JavaScript. Nothing is ever uploaded to any server—not even temporarily.
No waiting for server responses or upload progress bars. Processing starts immediately using your device's full computing power.
Once loaded, the tools work without an internet connection. Perfect for working on planes, in secure environments, or with unreliable connections.
Runs on Windows, Mac, Linux, ChromeOS, and mobile devices. Works in Chrome, Firefox, Safari, and Edge—no installation or plugins needed.
Not just toy demos—these are production-ready tools used daily by developers and data professionals.
Working with CSV data is a daily reality for data analysts, developers, and business professionals. Our CSV tools handle the tedious parts—merging files from different sources, removing duplicate rows, standardizing text formats, and cleaning up messy data exports. Process files with thousands of rows in seconds, not minutes.
The merge tool intelligently combines CSVs with different column structures, automatically creating a unified schema. The duplicate detector lets you specify which columns to check, so you can find exact matches or fuzzy duplicates based on key fields like email addresses or product IDs.
Debugging API responses, editing configuration files, or working with data exports shouldn't require switching between multiple tools. Our JSON formatter beautifies minified JSON with proper indentation and syntax highlighting, making nested objects and arrays easy to navigate and understand.
The validator doesn't just tell you something is wrong—it shows you exactly where the problem is with line numbers and context. Common issues like trailing commas, unquoted keys, and mismatched brackets are caught instantly with clear, actionable error messages.
Regular expressions are essential for developers, but they can be tricky to get right. Our regex tester provides instant visual feedback with live matching—see exactly what your pattern matches as you type. Highlighted results make it easy to verify your pattern works correctly.
The pattern explanation feature breaks down your regex into individual tokens, explaining what each part does. Combined with the code generator, you can quickly go from testing to production-ready code in JavaScript, Python, Go, or Java.
PDF manipulation is one of the most common document tasks, yet most tools require uploading your files to remote servers—a major privacy concern for sensitive documents. Our PDF tools process everything directly in your browser, making them safe for contracts, financial records, and confidential business documents.
Combine multiple PDFs into a single document with drag-and-drop ordering. Extract specific pages or split documents into individual files. Compress oversized PDFs for email attachments. Rotate, reorder, and delete pages with visual thumbnails showing exactly what you're working with.
YAML has become the standard for DevOps configuration—Kubernetes manifests, Docker Compose files, GitHub Actions workflows, and Ansible playbooks all use it. Our YAML tools help you format, validate, and convert YAML files without exposing sensitive infrastructure configs to third-party servers.
The formatter standardizes indentation and quote styles across your configs. Convert between YAML and JSON losslessly for debugging or API integration. Compare two YAML files side-by-side to catch differences in deployments or configuration drift.
JSON Web Tokens are everywhere in modern authentication, but debugging them often means pasting tokens into online tools—a significant security risk for production tokens. Our JWT decoder runs entirely in your browser, so your tokens and their claims never leave your device.
Instantly decode any JWT to view its header and payload claims. Check expiration times and issued-at timestamps with human-readable formatting. Generate parsing code for JavaScript, Python, Go, and other languages to integrate JWT handling into your applications.
Cron syntax is notoriously difficult to read and write correctly. A misplaced asterisk can mean the difference between running a job every minute versus every month. Our visual cron builder takes the guesswork out of scheduling by letting you build expressions with intuitive controls.
See exactly when your cron job will run with a preview of the next execution times. Get plain-English explanations of what your expression means. Start from common presets like 'every hour' or 'weekdays at 9am' and customize from there.
From individual developers to enterprise teams, our tools handle real-world data challenges.
Data preparation & cleaning
Prepare datasets for analysis by merging exports from multiple sources, removing duplicates, and standardizing formats before importing into Python, R, or Excel.
Example use case
“Combine monthly sales reports from 12 regional CSVs into a single clean dataset”
API debugging & configuration
Debug API responses by formatting and validating JSON payloads. Edit configuration files with confidence knowing syntax errors are caught immediately.
Example use case
“Format a 5000-line minified API response to find a nested configuration issue”
Report consolidation
Merge CRM exports, clean up customer lists, and prepare data for presentations—without waiting for IT support or learning complex software.
Example use case
“Deduplicate a customer list of 50,000 contacts exported from Salesforce”
Data processing
Process survey responses, combine experiment data, and prepare datasets for statistical analysis. Works on any computer without admin access.
Example use case
“Merge participant data from multiple research sites with different column formats”
Everything you need to know about using our tools.
We're supported by optional donations and minimal, privacy-respecting advertising. Since all processing happens in your browser, we don't incur server costs for file processing. This sustainable model lets us offer genuinely free tools without compromising your privacy.