Free File Converter Tools Online

Convert CSV to JSON, JSON to CSV, MP4 to MP3, MP3 to WAV, TXT to PDF and Markdown to PDF — free, instant, no signup.

✅ 31 free tools🔒 Files deleted in 2 hours⚡ Instant results📱 Works on mobile

All Converters — 31 Free Tools

Convert CSV files to JSON format instantly.

Convert JSON arrays to CSV spreadsheet format.

Convert plain text files to PDF documents.

Extract audio from MP4 video files.

Convert MP3 audio to WAV format.

Markdown to PDF

Convert Markdown documents to PDF.

KM to Miles Converter

Convert kilometres to miles and other distance units.

Celsius to Fahrenheit

Convert temperature between Celsius, Fahrenheit, and Kelvin.

KG to LBS Converter

Convert kilograms to pounds and other weight units.

Inches to CM Converter

Convert inches to centimetres and other length units.

Liters to Gallons Converter

Convert litres to US/UK gallons and other volume units.

Acres to Hectares Converter

Convert acres to hectares and other area units.

Bytes to KB Converter

Convert bytes to KB, MB, GB, and TB.

MPH to KM/H Converter

Convert miles per hour to km/h and other speed units.

PSI to Bar Converter

Convert PSI to bar and other pressure units.

Oz to Grams Converter

Convert ounces to grams and other small weight units.

Kcal to KJ Converter

Convert kilocalories to kilojoules and other energy units.

Cups to ML Converter

Convert cups to millilitres and other cooking volume units.

Speed Converter

Convert between m/s, km/h, mph, knots, and Mach.

Angle Converter

Convert between degrees, radians, gradians, and more.

Time Unit Converter

Convert between seconds, minutes, hours, days, weeks, and more.

Data Transfer Rate Converter

Convert between bps, Kbps, Mbps, Gbps, and MB/s.

Fuel Efficiency Converter

Convert between km/L, mpg (US/UK), and L/100km.

Shoe Size Converter

Convert shoe sizes between US, UK, EU, and CM for men and women.

Clothing Size Converter

Convert clothing sizes between US, UK, and EU with measurements.

Cooking Measurement Converter

Convert between teaspoons, tablespoons, cups, fl oz, mL, and liters.

Ring Size Converter

Convert ring sizes between US, UK, EU and diameter/circumference in mm.

Wind Speed Converter

Convert wind speed between m/s, km/h, mph, knots, and ft/s.

Force Converter

Convert force between Newtons, kilonewtons, pound-force, and more.

Frequency Converter

Convert frequency between Hz, kHz, MHz, GHz, and RPM.

Torque Converter

Convert torque between N·m, ft·lb, in·lb, and kgf·m.

What You Can Do with Converters

✓Convert CSV spreadsheets to JSON with automatic column detection
✓Export JSON arrays to CSV for Excel and Google Sheets
✓Convert plain text files to formatted PDF documents
✓Render Markdown to beautifully styled PDF with tables and code blocks
✓Extract MP3 audio from MP4, MOV, AVI, and MKV video files
✓Convert MP3 audio to uncompressed WAV format
✓Files automatically deleted after 2 hours
✓No file size limits for standard conversions

Who Uses Converters?

💻

Developers

Convert CSV exports to JSON for APIs and data pipelines

🎵

Content Creators

Extract audio from videos for podcasts and music

📝

Writers

Convert Markdown docs to shareable, printable PDFs

📊

Data Analysts

Switch between JSON and CSV for different tools

About Converters

File conversion is one of the most common everyday tasks for professionals, developers, and content creators alike. ToolNest's converter tools handle the most-needed format conversions in seconds, entirely in your browser with no software to install.

Whether you're a developer who needs to convert a CSV export to JSON for an API, a content creator extracting audio from a video file, or a writer turning a Markdown document into a polished PDF — ToolNest has you covered with fast, accurate, free conversions.

Frequently Asked Questions about Converters

Can I convert multiple files at once?

Each converter processes one file at a time. For batch conversions, submit each file separately — jobs run in parallel on our servers.

How does CSV to JSON work?

ToolNest reads the first row as column headers and converts each subsequent row into a JSON object, producing an array of objects as output.

What video formats does MP4 to MP3 support?

You can upload MP4, MOV, AVI, and MKV video files. The audio track is extracted and saved as a 192kbps MP3.

Is my data safe during conversion?

Yes. Files are uploaded over HTTPS, processed on secure servers, and automatically deleted within 2 hours. We never read, share, or retain your content.

Does Markdown to PDF support code blocks and tables?

Yes. Our Markdown renderer supports fenced code blocks, tables, blockquotes, and standard formatting — all styled in the output PDF.