What is a .arrow file?
Apache Arrow IPC File · Data · Apache Software Foundation · 2016
Apache Arrow is an in-memory columnar data format, and its file form (also known as Feather) stores that layout on disk. It lets tools share tabular data with zero copying, so reads are extremely fast.
What is a .arrow file used for?
An Arrow IPC file starts and ends with the magic ARROW1 around a columnar record batch. Because the on-disk layout matches the in-memory one, loading is nearly instant with no parsing, unlike CSV.
It is the backbone of the modern data stack (pandas, Polars, DuckDB, Spark). The .feather extension is the same format under an older name, favoured for fast local caching of data frames.
What opens a .arrow file?
The .arrow format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- Python (pyarrow, pandas)
- R (arrow)
- Polars
macOS
- Python (pyarrow, pandas)
- R (arrow)
- Polars
Linux
- Python (pyarrow, pandas)
- DuckDB
- Polars
Open a .arrow file step by step
- Confirm the file really is a .arrow. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with Python (pyarrow, pandas) or R (arrow).
- On Mac, use Python (pyarrow, pandas) or R (arrow).
- On Linux, try Python (pyarrow, pandas) or DuckDB.
- Still stuck? Convert the .arrow to parquet, which opens more widely.
Why can't I open my .arrow file?
Almost always because no installed app understands Arrow. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .arrow at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .arrow file
You can convert a .arrow file to parquet, csv, json using a conversion tool or the export menu of an app that opens it.
What is the .arrow file signature (magic bytes)?
A .arrow file starts with the hex bytes 41 52 52 4F 57 31, which read as ARROW1 in ASCII. Programs identify Arrow by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for Arrow. For a full breakdown, see the Apache Arrow / Feather file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 41 52 52 4F 57 31 | 0 | ARROW1 | 'ARROW1' |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .arrow file?
Apache Arrow is an in-memory columnar data format, and its file form (also known as Feather) stores that layout on disk. It lets tools share tabular data with zero copying, so reads are extremely fast.
What is the difference between Arrow and Parquet?
Arrow is a fast in-memory and IPC format for moving data between tools. Parquet is a compressed on-disk format for long-term columnar storage. They are complementary and interoperate.
Is Feather the same as Arrow?
Yes. Feather is the file form of the Apache Arrow format; a .feather file is an Arrow IPC file, popular for fast caching of data frames.
How do I open an .arrow file?
Read it with pyarrow or pandas in Python, the arrow package in R, or Polars. There is no document viewer; it is tabular data for code.
Related formats
Sources
Details on this page were checked against authoritative references. How sources are ranked and what is deliberately left out is set out in the methodology.