AVRO File

What are AVRO files and how to open them

Are you having problems opening an AVRO file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your AVRO files.

What is an AVRO file?

An .AVRO file is an Avro Serialized Data file.

Avro serialized data files store structured data in a compact binary format together with its schema. They are written by the Apache Avro system, primarily used for serializing records for storage or for sending across the network. Data, including every field value, is encoded according to a schema that describes the record types, primitive types (such as int, long, string, bytes, boolean, float, double, null), and complex types (like records, enums, arrays, maps, unions, and fixed). The schema is either embedded in the file or shared alongside it, enabling readers to decode the data without prior knowledge of its layout. It supports schema evolution, meaning new or changed schemas can interoperate with older data when fields are added, removed, or reordered in compatible ways.

The format is produced when data is serialized using Avro's object container file format. Such files contain a header that includes metadata - particularly the schema in JSON form - and then a sequence of data blocks. Each data block holds one or more records encoded according to that schema, possibly compressed using a codec such as null (no compression), deflate, snappy, etc. Between blocks Avro uses "sync markers," fixed-size random markers that help with splitting or scanning the file efficiently, for instance in distributed processing systems like Hadoop.

Files of this kind begin with a signature: the ASCII characters O, b, j, followed by a 0x01 byte. This magic header identifies the file as an Avro object container file. Immediately after that come the metadata, including a "schema" key whose value is the JSON schema definition, followed by a 16-byte sync marker.

How to open AVRO files

Important: Different programs may use files with the AVRO file extension for different purposes, so unless you are sure which format your AVRO file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 22, 2026

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