Is it really 100% offline?

Yes. Once installed, 1FileTool processes every single file entirely on your computer. There are no server calls, no uploads, no cloud processing. Your files never leave your device, ever.

What file formats are supported?

1FileTool supports 100+ file formats including PDF, JPG, PNG, WebP, SVG, GIF, MP4, MOV, AVI, MKV, MP3, WAV, FLAC, AAC, ZIP, CSV, XLSX, JSON, XML, HTML, Markdown, and many more.

Is there a free version?

Yes. 1FileTool is free to use with all 265+ tools and up to 8 files per day. Upgrade to Pro for unlimited processing with a one-time payment starting at $29.

How is this different from online tools like Smallpdf?

Online tools require uploading your files to their servers for processing. 1FileTool processes everything locally on your device, so your files never leave your computer. Plus, you pay once instead of monthly.

Does it work on both Mac and Windows?

Yes. 1FileTool is available as a native application for both macOS (Apple Silicon and Intel) and Windows (64-bit) with identical functionality.

Can an AI assistant use 1FileTool?

Yes. AI Access exposes 64 operations to Claude Code, Codex and Gemini over MCP. You ask for the work in plain language and your assistant sends instructions to the app on your machine — your files are never sent to the assistant.

Does the AI run on my computer?

Yes. Background removal, read-aloud, audiobook conversion, voice cleanup and PII detection all run on your device after a one-time model download. There is no AI API key and no per-use cost.

Convert between CSV, Excel and JSON

Turn a csv to excel, excel to csv, json to csv, csv to json, xml to json or markdown to html — locally, in bulk, with no upload size limit.

CSV to Excel, Excel to CSV, JSON to CSV and the reverse all run locally in one click — drop the file, pick the direction, get a converted file next to the original. Because nothing is uploaded, there is no size ceiling and no column count limit beyond what your machine can hold.

Protect your originals first

Replace source is ON by default: the output overwrites the original file and no backup is kept. Before following along, open Settings › General and turn Replace source off, or pick a separate output folder.

Conversions write a new file in your output folder — the source is never modified. The warning matters when you later chain these into a workflow that renames or strips files in place.

The converters

Tool	Direction	What you get
CSV to Excel	`.csv` → `.xlsx`	One workbook, one sheet, same rows.
Excel to CSV	`.xlsx` → `.csv`	The sheet's rows as comma-separated text.
JSON to CSV	`.json` → `.csv`	An array of objects becomes a table; a single object becomes a one-row table.
CSV to JSON	`.csv` → `.json`	First row becomes keys; each row below becomes an object.
XML to JSON	`.xml` → `.json`	The element tree becomes nested JSON.
JSON to XML	`.json` → `.xml`	Objects become elements, wrapped in a standard XML declaration.
Markdown to HTML	`.md` → `.html`	Rendered markup you can open in a browser.

What to expect

JSON ↔ CSV is for flat data. CSV is a grid of cells, so json_to_csv works on an array of objects — keys become headers, values become cells. Nested objects don't round-trip back into nested JSON; keep those as XML or restructure first.

CSV → JSON uses the header row as keys. Every value lands as a string — CSV carries no types, so "42" stays "42" until your code parses it.

Quoting is handled. Commas, quotes and newlines inside a field are escaped per the CSV convention, so Smith, John converts cleanly.

Large files stay local. A 500 MB export converts at disk speed — no upload progress bar, no "file too large" wall, no rows lost to a web form's limits.