--- title: MailerLite API Integration on Truto slug: mailerlite category: Marketing Automation canonical: "https://truto.one/integrations/detail/mailerlite/" --- # MailerLite API Integration on Truto **Category:** Marketing Automation **Status:** Generally available ## Unified APIs ### Unified Marketing Automation API - **Contacts** — The contact represent a contact in the remote system. - **Lists** — The list represent a list of contacts in the remote system. - **Segments** — Represents a segment of contacts in the remote system. ## How it works 1. **Link your customer's MailerLite account.** Use Truto's frontend SDK; we handle every OAuth and API key flow so you don't need to create the OAuth app. 2. **Authentication is automatic.** Truto refreshes tokens, stores credentials securely, and injects them into every API request. 3. **Call Truto's API to reach MailerLite.** The Proxy API is a 1-to-1 mapping of the MailerLite API. 4. **Get a unified response format.** Every response uses a single shape, with cursor-based pagination and data in the `result` field. ## Use cases - **Sync event registrants into MailerLite for automated follow-up** — Event and webinar platforms can push attendee data directly into MailerLite Groups, letting organizers trigger automated pre-event reminders and post-event nurture sequences without manual CSV exports. - **Route form submissions into MailerLite with rich contact profiles** — Form builders and survey tools can map form fields to MailerLite custom fields and upsert contacts on submission, giving end users instant, well-structured leads ready for segmented email campaigns. - **Push purchase and enrollment data for creator monetization workflows** — Course platforms and e-commerce tools can write custom field data like course name or order value into MailerLite contacts, enabling creators to build behavior-driven cross-sell and re-engagement automations. - **Keep CRM contact status in sync with MailerLite subscription state** — Sales CRMs need to reflect when a lead unsubscribes or bounces in MailerLite so reps never email opted-out contacts, maintaining GDPR and CAN-SPAM compliance across systems. - **Let users target specific MailerLite segments from within your product** — SaaS platforms can fetch a user's MailerLite Segments and Lists, display them in-app, and let users select audiences for targeted actions — bridging marketing data into product workflows without context-switching. ## What you can build - **One-click subscriber upsert on form submission** — Automatically create or update a MailerLite contact with mapped custom fields every time a user submits a form, survey, or registration in your product. - **In-app MailerLite Group picker for audience routing** — Fetch your end user's MailerLite Groups (Lists) via Truto and render them in a dropdown so users can map product events to specific groups without leaving your UI. - **Custom field mapping interface** — Pull MailerLite custom fields and let users visually map your product's data points to those fields, ensuring rich contact profiles land in MailerLite on every sync. - **Segment-aware audience selector** — Read MailerLite Segments and their member contacts so users can target dynamic audiences directly from your product for re-engagement, reporting, or CRM sync workflows. - **Unsubscribe and bounce webhook listener for compliance sync** — Listen for MailerLite unsubscribe and bounce events and automatically flag contacts as 'Do Not Contact' inside your platform to keep sales and support teams compliant. - **Automated group assignment on lifecycle events** — When a user completes a purchase, finishes onboarding, or hits a milestone in your product, assign their MailerLite contact to a designated Group to kick off the right automation sequence. ## FAQs ### How does Truto handle authentication with MailerLite? MailerLite uses API key-based authentication. Truto manages the credential storage and injection so your application never handles raw API keys directly. Your end users provide their MailerLite API key through Truto's auth flow. ### Does MailerLite support contact upserts or do I need to check for duplicates manually? MailerLite's API natively supports upserting subscribers by email address. You can create or update a contact in a single call without worrying about duplicate errors, which maps cleanly to the Contacts resource in the Unified Marketing Automation API. ### What is the difference between Groups and Segments in MailerLite? Groups are static, manually managed collections of subscribers — equivalent to Lists in Truto's unified model. Segments are dynamic, rule-based audiences generated by MailerLite (e.g., 'opened email in last 7 days'). Segments are read-only from an integration perspective; you can list them and fetch their members but cannot add contacts to them directly. ### Are there rate limits on the MailerLite API I should know about? Yes, MailerLite's API v3 enforces rate limits. Truto handles retry logic and pagination automatically, but high-volume bulk syncs should be designed with batching in mind to avoid throttling. ### Can I sync custom fields from my product into MailerLite contact records? Yes. MailerLite supports custom fields on subscriber records. Through Truto, you can read available custom fields and write values to them when creating or updating contacts, enabling rich segmentation inside MailerLite based on your product's data. ### Is this integration available today or built on request? The MailerLite integration through Truto's Unified Marketing Automation API is built on request. Contact Truto to initiate setup — the typical turnaround is fast since MailerLite's API v3 maps well to the unified Contacts, Lists, and Segments primitives.