> ## Documentation Index
> Fetch the complete documentation index at: https://sdk.umbraprivacy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Batch Merkle Proofs

> Retrieve multiple Merkle inclusion proofs atomically under the same tree root.

## Endpoint

`POST /v1/trees/{tree_index}/proofs`

Returns multiple Merkle inclusion proofs for the specified insertion indices, all guaranteed to be computed against the same tree root. This is what the V18 burner factory calls per batch — burns that bundle multiple Stealth Pool Notes need all proofs to share a root.

## Path Parameters

* `tree_index` (u64) -- Zero-based index of the Merkle tree.

## Request Body

JSON object with a single field:

* `insertion_indices` (array of u64) -- Leaf positions to generate proofs for. Maximum 8 indices per request.

**Example:**

```json theme={null}
{
  "insertion_indices": [42, 108, 255]
}
```

## Response

Protobuf `BatchProofResponse` containing an array of proof objects. Each proof has the same structure as the single proof endpoint:

* `root` (string) -- 64-character little-endian hex-encoded Poseidon root hash. Identical across all proofs in the batch.
* `tree_index` (int64) -- Echo of the path parameter.
* `insertion_index` (int64) -- The leaf position this proof corresponds to.
* `proof` (array of 20 strings) -- Sibling hashes from leaf to root, each 64-character hex.
* `leaf` (string) -- 64-character hex-encoded final commitment.

## Why Batch?

Single proof requests (`GET /v1/trees/{tree_index}/proof/{insertion_index}`) do not guarantee a consistent root across multiple calls — the tree may grow between requests. The batch endpoint acquires a read lock on the tree, ensuring all returned proofs share the same root. This is required for Groth16 ZK proofs that reference multiple note commitments.

<Note>
  The SDK's burner factories call this endpoint internally per batch. Receiver-burnable → ETA burns chunk to ≤5 notes per proof; self-burnable burners loop one note at a time.
</Note>