---
title: "List carbon factor versions"
method: GET
path: "/api/v1/carbon-factors"
tags: ["Factors"]
---

# List carbon factor versions

`GET /api/v1/carbon-factors`

## Request

- Base URL: `https://api.crbonfree.com`
- URL: `https://api.crbonfree.com/api/v1/carbon-factors`
- Auth: one of:
  - HTTP bearer
  - API key in header `X-API-Key`
- TypeScript: <https://skmtc.dev/crbonfree/apis/crbonfree-api/docs/api/v1/carbon-factors/get.ts> (a function with typed inputs; its response is checked against the schema)

Returns every emissions factor version, oldest first, with whether it is the active writer version and whether it carries the v1.2 layered-emissions factors.

## Response `200`

Factor versions

- object
  - `success` true, required
  - `data` CarbonFactorVersionList, required
    - `versions` CarbonFactorVersionSummary[], required
      - `version` string, required
      - `active` boolean, required
      - `layered` boolean, required
      - `tierCount` integer, required
      - `createdAt` string, required

## Other responses

- `400`: Bad request — validation failed or malformed JSON body
- `401`: Unauthorized — token missing, expired, or invalid
- `429`: Too many requests — rate limit exceeded
- `500`: Internal server error
- `503`: Factor configuration is inconsistent or the active version is not seeded

## Changes

- **2026-09-08** `7703acd56f0a`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/crbonfree/apis/crbonfree-api/changes/api/v1/carbon-factors/get.md)

---

[API](https://skmtc.dev/crbonfree/apis/crbonfree-api.md) - [All operations](https://skmtc.dev/crbonfree/apis/crbonfree-api/llms.txt) - [OpenAPI document](https://skmtc.dev/crbonfree/apis/crbonfree-api/revisions/a21ffdb80e67?raw)