---
title: "Upload a Nakamoto block"
method: POST
path: "/v3/blocks/upload"
tags: ["Blocks"]
---

# Upload a Nakamoto block

`POST /v3/blocks/upload`

Upload a Nakamoto block to the node for processing.

- **Body** - must be the binary (SIP-003) serialization of a `NakamotoBlock`.
- **Authentication** - only required when the query parameter `broadcast=1` is supplied.
  In that case the caller **must** include an `Authorization` header.

## Query parameters

- `broadcast` '1'

## Response `200`

Block upload result.

- BlockUploadResponse — unresolved $ref

## Other responses

- `400` — Bad request
- `401` — Unauthorized. Invalid or missing authentication token.
- `500` — Internal Server Error

## Changes

- **2026-01-28** `30468ca2533f` — 1 breaking
  - the request's body minLength was increased from `0` to `1`
- **2026-01-14** `f7f733b4a1fc` — 1 info
  - the request's body minLength was decreased from `1` to `0`
- **2026-01-14** `eb2153a4a3ad` — 1 breaking
  - the request's body minLength was increased from `0` to `1`
- **2026-01-02** `96224b968a3e` — 1 info
  - the request's body minLength was decreased from `1` to `0`
- **2025-12-18** `97e7080a8130` — 1 breaking
  - the request's body minLength was increased from `0` to `1`

[Full history](https://skmtc.dev/stacks-network/apis/stacks-3-0-rpc-api/changes/v3/blocks/upload/post.md)

---

[API](https://skmtc.dev/stacks-network/apis/stacks-3-0-rpc-api.md) · [All operations](https://skmtc.dev/stacks-network/apis/stacks-3-0-rpc-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/stacks-network/stacks-3-0-rpc-api/revisions/bfe6e0b30f62/schema)