> ## Documentation Index > Fetch the complete documentation index at: https://developer.lemlist.com/llms.txt > Use this file to discover all available pages before exploring further. > Selects the winning A/B test variant, applied to all remaining leads. # Select A/B Test Winner A/B testing requires at least the **Email Pro** plan. Concludes the A/B test by selecting the winning variant. From then on, **all remaining leads** going through the step receive the winning template — the split stops and the winner is sent every time. Both templates are kept on the step, so you can inspect the loser afterwards. ## Request Body | Field | Type | Description | | --------- | ----------------- | ------------------------------- | | `variant` | string (required) | The winning variant: `A` or `B` | ```json theme={"theme":"dracula"} { "variant": "B" } ``` This is allowed while the campaign is running — selecting a winner mid-flight is the intended use. Selecting a winner is **final**: a second selection returns `400`. If the step does not run an A/B test, the endpoint returns `404`. ## OpenAPI ````yaml post /sequences/{sequenceId}/steps/{stepId}/ab-test/winner openapi: 3.0.0 info: title: lemlist API version: 1.0.0 description: >- Welcome to the lemlist Developer Documentation. lemlist is very customizable and open. You'll find on this page all the API and integration you can do with lemlist. # Rate Limit lemlist's API rate limits requests in order to prevent abuse and overload of our services. Rate limits are applied on all routes and per API key performing the request. The rate limits are **20** requests per **2** seconds. The response provides any information you may need about it: | Header | Description | | --- | --- | | Retry-After | The number of seconds in which you can retry | | X-RateLimit-Limit | The maximum requests in that time | | X-RateLimit-Remaining | The number of remaining requests you can make | | X-RateLimit-Reset | The date when the rate limit will reset | _Example of values for the rate limit headers_ ``` json { "Retry-After": 2, "X-RateLimit-Limit": 20, "X-RateLimit-Remaining": 7, "X-RateLimit-Reset" : "Tue Feb 16 2021 09:02:42 GMT+0100 (Central European Standard Time)" } ``` # Definitions ## Team A team is the entity of lemlist that can handle users and billing. ## Credits Credits are the coins a team uses to enrich emails, LinkedIn URLs, etc. via the enrich route. Each enrichment feature needs a certain amount of credits to run. ## User You use a user account to connect to lemlist and send messages via the connected emails or LinkedIn account. ## Campaign A campaign is the entity to automate outreach. A campaign has multiple sequences composed of steps. ## Lead A lead is a person that you try to contact via a campaign. ## Activity An activity is the history of all the steps. ## Unsubscribe An unsubscribe occurs when a person decides they don't want to receive emails from you anymore. # Authentication All API routes use the dedicated subdomain `api.lemlist.com`. lemlist uses API keys to allow access to the API. You can get your lemlist API key at our [integration page](https://app.lemlist.com/settings/integrations). You need to add the `Authorization` header using the `Basic` authentication type. `login:password` **where the login is always empty and the password is the API key**. ⚠️ **Don't forget to add the semicolon (**`:`**) before your API key in curl command.** > To authorize, use this code: ``` shell curl https://api.lemlist.com/api/team \ --user ":YourApiKey" ``` **Make sure to replace** **`YourApiKey`** **with your API key.** # Give feedback If you want to report a bug, ask for data, or share with us a use case, please fill this [form](https://lemlist.typeform.com/to/mfVlkyGf). It will help us centralize your needs! servers: - url: https://api.lemlist.com/api security: - basicAuth: [] paths: /sequences/{sequenceId}/steps/{stepId}/ab-test/winner: parameters: - name: sequenceId in: path required: true description: The unique identifier of the sequence example: seq_lkCSKd32qSZZTe5Ru schema: type: string - name: stepId in: path required: true description: The unique identifier of the step example: stp_V0JHmSpWiO0rxHUkz schema: type: string post: tags: - Sequences summary: Select A/B Test Winner description: >- Selects the winning variant of the A/B test. The winning template is then sent to all remaining leads going through the campaign. Requires the Email Pro plan. parameters: [] requestBody: required: true content: application/json: schema: type: object required: - variant properties: variant: type: string enum: - A - B description: The winning variant example: variant: B responses: '200': description: Winner selected content: application/json: schema: type: object properties: stepId: type: string abTest: type: string enum: - A - B example: stepId: stp_V0JHmSpWiO0rxHUkz abTest: B '400': description: >- A winning variant has already been selected, or the variant is invalid content: text/plain: example: A winning variant has already been selected for this step '401': description: The authentication you supplied is incorrect content: text/plain: example: The authentication you supplied is incorrect '402': description: A/B testing requires at least the Email Pro plan content: text/plain: example: route is available starting emailPro plan '404': description: Sequence, step, or A/B test variant not found content: text/plain: example: No A/B test variant on this step '405': description: Method not allowed components: securitySchemes: basicAuth: type: http scheme: basic ````