---
title: "Changes to Start a new browser session"
method: POST
path: "/v1/sessions/start"
---

# Changes to Start a new browser session

`POST /v1/sessions/start`

> Every recorded change to this operation, newest first.

## Timeline

Changed in 4 of 12 revisions.

- **2026-09-15** `0572d68a1e5e`: 3 breaking, 1 info
- **2026-05-07** `09241a1f0ee0`: 5 info
- **2026-03-24** `975ca868b31b`: 1 info
- **2026-01-27** `089c8670f1d7`: 1 warning, 1 info

## Changes

- **2026-09-15** `0572d68a1e5e`: 3 breaking, 1 info
  - removed `subschema #2: ProxyConfigList` from the `browserbaseSessionCreateParams/proxies` request property `anyOf` list
  - added 'propertyNames' constraint to the request property `browser/launchOptions/cdpHeaders`
  - added 'propertyNames' constraint to the request property `browserbaseSessionCreateParams/userMetadata`
  - added `subschema #2` to the `browserbaseSessionCreateParams/proxies` request property `anyOf` list
- **2026-05-07** `09241a1f0ee0`: 5 info
  - added the new optional request property `browserbaseSessionCreateParams/browserSettings/captchaImageSelector`
  - added the new optional request property `browserbaseSessionCreateParams/browserSettings/captchaInputSelector`
  - added the new optional request property `browserbaseSessionCreateParams/browserSettings/os`
  - added the new optional request property `browserbaseSessionCreateParams/browserSettings/verified`
  - request property `browserbaseSessionCreateParams/projectId` deprecated
- **2026-03-24** `975ca868b31b`: 1 info
  - added the new optional request property `browser/launchOptions/cdpHeaders`
- **2026-01-27** `089c8670f1d7`: 1 warning, 1 info
  - deleted the `header` request parameter `x-sent-at`
  - added the new optional request property `browser/launchOptions/port`

---

[Operation](https://skmtc.dev/browserbase/apis/stagehand-api/docs/v1/sessions/start/post.md) - [API](https://skmtc.dev/browserbase/apis/stagehand-api.md) - [Page](https://skmtc.dev/browserbase/apis/stagehand-api/changes/v1/sessions/start/post)