---
title: "Create a span note"
method: POST
path: "/v1/span_notes"
tags: ["spans"]
---

# Create a span note

`POST /v1/span_notes`

Add a note annotation to a span. Notes are special annotations that allow multiple entries per span (unlike regular annotations which are unique by name and identifier). Each note gets a unique UUIDv4 identifier.

## Request body

- CreateSpanNoteRequestBody
  - `data` SpanNoteData, required
    - `span_id` string, required — OpenTelemetry Span ID (hex format w/o 0x prefix)
    - `note` string, required — The note text to add to the span

## Response `200`

Span note created successfully

- CreateSpanNoteResponseBody
  - `data` InsertedSpanAnnotation, required
    - `id` string, required — The ID of the inserted span annotation

## Other responses

- `403` — Forbidden
- `404` — Span not found
- `422` — Validation Error

## Changes

- **2026-04-29** `c81391216eb5` — 1 warning
  - removed the request property `data/identifier`

[Change history](https://skmtc.dev/arize-ai/apis/arize-phoenix-rest-api/changes/v1/span_notes/post.md)

---

[API](https://skmtc.dev/arize-ai/apis/arize-phoenix-rest-api.md) · [All operations](https://skmtc.dev/arize-ai/apis/arize-phoenix-rest-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/arize-ai/arize-phoenix-rest-api/revisions/885be87470ca/schema)