What Is an Arweave Bundle? (ANS-104)

An Arweave Bundle is a single on-chain transaction that contains many individual data-items. Bundles let you group, upload, and retrieve multiple payloads in one go—saving on transaction fees and network overhead.

1. Data-Items Recap

A data-item is the fundamental Arweave payload format. Each data-item consists of:

A fixed‐length header (version, owner, target, anchor)
A tag list (key/value metadata)
The binary content (your file or JSON)
A signature by the owner’s Arweave key

Individually, each data-item must be posted as its own transaction. Bundling lets you batch them.

2. Why Bundle?

Lower Fees: One transaction fee instead of N fees for N items.
Simpler Retrieval: Fetch related items together.
Parallel Uploads: Clients can pipeline many data-items then bundle at once.

3. ANS-104 Bundle Format (v2)

A bundle is a binary blob structured as: