> ## 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. # Create Lead in Campaign > Creates a new lead and adds it to a specific campaign. Never updates an existing lead. export const SnippetObjectReference = ({objectName, objectPath = null}) => { const lowerCaseObjectName = objectName.toLowerCase(); if (lowerCaseObjectName === 'lead' || lowerCaseObjectName === 'leads') { return This endpoint uses the {objectName} object. Make sure to also check the {lowerCaseObjectName === 'lead' ? 'Contact' : 'Lead'} object to understand the distinction between the two. ; } return This endpoint uses the {objectName} object. ; }; **This endpoint creates, it never updates.** A contact that already has a lead in this campaign is refused with `400 LEAD_ALREADY_IN_CAMPAIGN`, nothing written; use `PATCH /campaigns/{campaignId}/leads/{leadId}` instead. With `deduplicate=true`, a contact with a lead in another campaign is refused with `409 LEAD_ALREADY_IN_OTHER_CAMPAIGN`; only this parameter drives that check, not the campaign's "remove duplicates" setting. The lead is always new, but the contact and the company it matches are updated with the fields you send; `updateStrategy` decides what they keep. `overwrite` (default): sent values replace stored ones, an empty value clears. `overwriteIgnoreEmpty`: same, empty values ignored. `fillEmptyOnly`: only empty fields are filled, identifiers, company link, owner and status kept, and the lead takes the values the contact kept. Kept values are listed in `warnings` (`FIELDS_KEPT`, `params.fields`, company fields prefixed with `company`). Beyond the standard fields above, **any additional key/value pair you send in the body is stored as a custom variable** on the lead and can be used in your campaign with `{{yourVariableName}}`. In the example, `companySize` and `customVariable1` are custom variables. Naming rules: only letters, digits, `_`, `-`, space and `#` are kept — any other character (e.g. `.` or `$`) is replaced by `_`. Values are stored as text. Company fields — `companyName`, `companyDomain`, `companyIndustry`, any `company`-prefixed key — reach the **company record** the lead is matched to, the same record every other lead linked to it reads, not that lead alone. Creating a lead with its company is the intended flow; to edit a company on purpose, use [Upsert Company](/api-reference/endpoints/companies/upsert-company). ## OpenAPI ````yaml post /campaigns/{campaignId}/leads/ 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: [] tags: - name: Enrichment Providers description: >- The data providers lemlist can call to find an email or a phone. Internal providers are paid with lemlist credits and always available. External providers run on your own account: connect one by saving its API key, and it becomes available to your waterfalls. `GET /enrichments/providers` is the catalog of provider ids accepted by the waterfall endpoints. - name: Enrichment Waterfalls description: >- Control which data providers lemlist calls when enriching a contact, and in which order. A waterfall is an ordered list of providers for one enrichment `type` (`email` or `phone`). Providers are tried one after the other until one returns a result. Every team has exactly one default waterfall per type (`isDefault: true`). While its `editor` is `lemlist` it follows the lemlist behaviour: providers you connected with your own API key are tried first, then internal providers in a random order. Once a team member edits its provider list, `editor` becomes that user's id and the list is followed as is; resetting it hands it back to `lemlist`. Custom waterfalls (`isDefault: false`) carry `conditions` on the contact being enriched, keyed by contact property; every key present must match. When a contact is enriched, lemlist runs a single waterfall: the custom waterfall of the requested type whose conditions match the contact, or the default waterfall when none does. If several match, the one with the most condition keys wins, then the most recently updated. Only that waterfall runs; when it finds nothing, the enrichment ends without falling back to another one. paths: /campaigns/{campaignId}/leads/: parameters: - name: campaignId in: path required: true description: The unique identifier of the campaign example: cam_A1B2C3D4E5F6G7H8I9 schema: type: string post: tags: - Leads summary: Create Lead in Campaign description: >- Creates a new lead in the campaign, never updates one: a contact that already has a lead in this campaign is refused with `400 LEAD_ALREADY_IN_CAMPAIGN` and nothing is written, on the lead, the contact or the company. Use `PATCH /campaigns/{campaignId}/leads/{leadId}` to change an existing lead. The contact and the company the new lead belongs to may already exist: `updateStrategy` decides how their stored values are updated, and under `fillEmptyOnly` the created lead takes the values the contact kept. parameters: - name: deduplicate in: query required: false description: >- Refuse the lead with `409 LEAD_ALREADY_IN_OTHER_CAMPAIGN` when the contact already has one in another campaign. Default: false. The campaign's own "remove duplicates" setting does not apply here. example: 'true' schema: type: boolean - name: linkedinEnrichment in: query required: false description: 'Run the LinkedIn enrichment. Default: false' example: 'true' schema: type: boolean - name: findEmail in: query required: false description: 'Find verified email. Default: false' example: 'true' schema: type: boolean - name: verifyEmail in: query required: false description: 'Verify existing email (debounce). Default: false' example: 'true' schema: type: boolean - name: findPhone in: query required: false description: 'Find phone number. Default: false' example: 'true' schema: type: boolean - name: updateStrategy in: query required: false description: >- What the matched contact and company keep (the lead is always created). `overwrite` (default): sent values replace stored ones, an empty string clears. `overwriteIgnoreEmpty`: empty values ignored. `fillEmptyOnly`: only empty fields filled, identifiers, links, owner and status kept. Other values: 400. example: fillEmptyOnly schema: type: string enum: - overwrite - overwriteIgnoreEmpty - fillEmptyOnly default: overwrite requestBody: content: application/json: schema: type: object properties: email: type: string description: Email of the lead firstName: type: string description: First name of the lead lastName: type: string description: Last name of the lead companyName: type: string description: Company name jobTitle: type: string description: Job title linkedinUrl: type: string description: LinkedIn profile URL picture: type: string description: Profile picture URL phone: type: string description: Phone number companyDomain: type: string description: Company domain icebreaker: type: string description: Personalized icebreaker message timezone: type: string description: >- Lead's timezone in IANA format (e.g., Europe/Paris, America/New_York) contactOwner: type: string description: Contact owner (user ID or user login email) additionalProperties: type: string example: email: support@lemlist.com firstName: John lastName: Doe companyName: lemlist jobTitle: Developer linkedinUrl: https://www.linkedin.com/in/johndoe phone: +33 123456789 timezone: Europe/Paris contactOwner: login_email@lemlist.com companySize: 50-100 customVariable1: any value you want responses: '200': description: Success content: application/json: schema: type: object properties: campaignId: type: string campaignName: type: string email: type: string format: email firstName: type: string lastName: type: string companyName: type: string jobTitle: type: string companyDomain: type: string _id: type: string isPaused: type: boolean description: Whether the lead is paused in the campaign contactId: type: string description: Associated contact ID warnings: type: array description: >- Non-blocking notices, never a failure — the request went through. They tell you why the company part was skipped, when it was, and which values the update strategy kept. See `code`. items: type: object properties: code: type: string description: >- **The company was NOT written**: `invalid-company-domain`, `invalid-company-linkedin-url`, `company-linkedin-url-not-company` (malformed identifier, or a personal profile URL), `company-duplicate-forbidden` (an identifier already belongs to another company), `company-update-failed` (the write failed). The lead itself went through in every case. **The company domain was dropped**: `COMPANY_DOMAIN_IGNORED`, `companyDomain` is a personal email provider or a platform host shared by many companies (`gmail.com`, a `facebook.com` page, a bare `wordpress.com`). The lead and its company went through without it; `params.companyDomain` names it. **Values left unchanged**: `FIELDS_KEPT`, what the update strategy kept, named in `params.fields` (company fields prefixed with `company`). message: type: string params: type: object additionalProperties: anyOf: - type: string - type: array items: type: string description: >- Details: the input echoed back, or `fields` for `FIELDS_KEPT`. example: campaignId: cam_bSn8EORHQxbWPjHvu campaignName: NEW TO DELETE firstName: John lastName: Doe companyName: lemlist jobTitle: GTM Engineer companyDomain: example.com email: support@lemlist.com _id: lea_fiDpiGV585wy3Oii2 isPaused: false contactId: ctc_xW8Ou6C03Csv8vatp '400': description: >- Possible errors: No API key provided / Bad team / Body of your request must be an object / Invalid email address / Invalid LinkedIn URL / LinkedIn URL is not a personal profile / Email address is in the graveyard / Lead already in the campaign / No valid fields to add / Invalid updateStrategy value content: text/plain: example: No API key provided '401': description: The authentication you supplied is incorrect content: text/plain: example: The authentication you supplied is incorrect '403': description: User linked to this API key is blocked content: text/plain: example: User linked to this API key is blocked '404': description: 'Possible errors: No user found for this API key / Campaign not found' content: text/plain: example: No user found for this API key '405': description: >- Malformed path segment. Possible errors: Invalid email address / Invalid lead identifier content: application/json: example: error: Invalid email address '409': description: >- Possible errors: Lead already in other campaign / An identifier (email, linkedinUrl or salesnavUrl) already belongs to another contact content: text/plain: example: Lead already in other campaign components: securitySchemes: basicAuth: type: http scheme: basic ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.