--- title: "Connect Quaderno to Lettr - APIANT.ai" description: "When \"New Contact\" fires in Quaderno, your agent runs \"Add contact\" in Lettr." canonical: "https://apiant.ai/connect/quaderno-to-lettr" --- # Connect Quaderno to Lettr When **New Contact** fires in [Quaderno](https://apiant.ai/connections/quaderno), your agent runs **Add contact** in [Lettr](https://apiant.ai/connections/lettr). Describe the whole flow and it is built, tested on every scenario and kept running. Quaderno **3** triggers Quaderno **24** actions Lettr **11** actions What the catalog holds today. Ask for anything missing and your agent reads the API documentation and adds it. ## What do you want Quaderno and Lettr to do together? Give your AI client this address. `https://mcp.apiant.ai` One connection does both: ask your client to act in an app once, or have it build an automation that keeps running. Any client that takes a remote MCP server. Nothing to install. Create your free account, then sign in once in your browser. ### Set it up in your client ### Claude Code Run this in the directory you want to work in. `claude mcp add --transport http -s project apiant-ai https://mcp.apiant.ai` Start Claude Code there, approve the server, and sign in in the browser page it opens. [Claude Code guide (opens in a new tab)](https://apiant.ai/docs/mcp/claude-code) ### Claude, web and desktop Open Customize, then Connectors, then Add custom connector, and paste the address. On Team and Enterprise an owner adds it first. [Setup guide (opens in a new tab)](https://apiant.ai/docs/mcp) ### Cursor Add the address to your MCP configuration as a server URL. Cursor signs you in in your browser. [Setup guide (opens in a new tab)](https://apiant.ai/docs/mcp) ### Zed Open Settings, then AI, then MCP Servers, then Add Server, then Add Remote Server. [Setup guide (opens in a new tab)](https://apiant.ai/docs/mcp) ### Codex and the ChatGPT desktop app Open Settings, then MCP servers, then Add server, and choose Streamable HTTP. From the terminal, Codex takes the address with its own add command and then signs you in. [Setup guide (opens in a new tab)](https://apiant.ai/docs/mcp) ### Any other MCP client Paste the address where the client asks for a remote MCP server URL, and name the server apiant-ai where it lets you. APIANT's skills reach the client over the same connection. [Setup guide (opens in a new tab)](https://apiant.ai/docs/mcp) Example flows ## What Quaderno can start in Lettr - When **New Contact** in Quaderno then **Add contact** in Lettr - When **New Invoice** in Quaderno then **Add contact to list** in Lettr Starting points drawn from the triggers and actions in the catalog today. Describe the flow you need, at any depth, and your agent builds it and tests every scenario before it ships. Everything your agent can do with Quaderno and Lettr ## Triggers and actions 3 triggers · 35 actions - Trigger **New Contact** Triggers when a new contact is created in Quaderno. - Trigger **New Invoice** Triggers when a new invoice is created in Quaderno. - Trigger **New Sale** Triggers when a new sale is recorded in Quaderno, i.e. a new invoice or receipt is created. - Action **Add invoice payment** Records a payment against a Quaderno invoice. When total payments reach the invoice amount, the invoice is marked as paid. - Action **Add product** Creates a new product in Quaderno that can be used as a line item on invoices, credit notes and expenses. - Action **Add receipt** Creates a paid receipt in Quaderno for a completed sale, with its customer, line items and payment method. - Action **Calculate tax rate** Calculates the tax rate and tax amount that applies to a sale for a given customer location and product type. - Action **Create Contact** Creates a new contact (customer or vendor) in Quaderno and returns the created contact. - Action **Create Estimate** Creates an estimate (proforma) in Quaderno for a customer, with line items, dates and notes. - Action **Create Expense** Creates an expense in Quaderno for a vendor, with its line items, and returns the new expense. - Action **Create Invoice** Creates an invoice for a customer with line items; optionally records full payment so the invoice is marked paid. - Action **Create Paid Invoice** Creates an invoice for a customer and records a full payment against it, so the invoice is marked paid. - Action **Create Sale** Records a sale in Quaderno, which calculates taxes and issues the matching invoice or receipt for the customer. - Action **Delete contact** Permanently deletes a contact (customer or vendor) from your Quaderno account. - Action **Find Contact** Finds contacts whose name, email or tax ID matches the search text, or whose payment-processor ID matches. - Action **Find Sale** Finds sales (invoices) by invoice number, customer name or PO number, payment processor transaction id, customer, state or issue date range, and returns the matches. - Action **Get contact** Returns a single Quaderno contact (customer or vendor) by its ID. - Action **Get Estimate** Returns a single estimate (proforma) by its id, including its number, customer, line items, taxes and totals. - Action **Get Expense** Returns the details of an existing expense in your Quaderno account. - Action **Get invoice** Returns a single invoice by its id, including number, contact, line items, taxes, totals and payments. - Action **Get product** Returns a single product (item) from your Quaderno account by its id, including its name, code, price and tax settings. - Action **Get Receipt** Returns a receipt by its id, including number, totals, taxes, contact and payment details. - Action **Update contact** Updates an existing Quaderno contact. Fields left blank keep their current values. - Action **Update invoice** Updates the editable fields of an existing invoice: PO number, tags, payment details, notes, custom metadata and billing address. - Action **Update product** Updates an existing product in Quaderno. Only the fields you fill in are changed. - Action **Validate tax ID** Checks whether a customer's tax ID (EU/UK VAT, ABN, NZBN, QST, Swiss UID) is valid and belongs to a real business. - Action **Void invoice** Voids an existing invoice in Quaderno and returns the voided invoice. - Action **Add audience list** Creates a new audience list in Lettr with the given name and returns the created list. - Action **Add contact** Adds a new contact to your Lettr audience, optionally placing it on a list, setting custom properties, and sending a double opt-in confirmation email. - Action **Add contact to list** Adds an existing contact to one of your audience lists. Succeeds whether the contact was newly added or was already on the list. - Action **Add template** Creates a new email template in Lettr from HTML or Topol editor JSON content, and publishes its first version with the merge tags found in the content. - Action **Delete contact** Permanently deletes a contact from your Lettr audience. - Action **Get contact** Returns a single audience contact, including its subscription status, custom properties, lists and topics. - Action **Get template** Returns a single email template by its slug, including its HTML, editor content, purpose, status and version details. - Action **List audience lists** Returns all audience lists in your Lettr team, with each list's name and contact count. - Action **List contacts** Returns the contacts in your Lettr audience, optionally narrowed by a search term, subscription status, list or segment. - Action **List templates** Returns the email templates in a Lettr project, optionally limited to one folder or to transactional or campaign templates. - Action **Update contact** Updates an existing contact in your Lettr audience, changing its email address, subscription status or custom properties. Fields left blank are not changed. ## Each app on its own - [ **Quaderno** Quaderno is a tax software that handles sales tax, VAT, and GST for your online business.](https://apiant.ai/connections/quaderno) - [ **Lettr** Lettr is a email API for artisans, send transactional emails using HTML or stored templates.](https://apiant.ai/connections/lettr) Reviews ## What our customers say ## More from Quaderno - [ **Quaderno to Hyperstack Certificates** Hyperstack helps you easily create and manage digital certificates & badges for your events or courses.](https://apiant.ai/connect/quaderno-to-hyperstack-certificates) - [ **Quaderno to Salesforce** Salesforce is a leading enterprise customer relationship management (CRM) platform.](https://apiant.ai/connect/quaderno-to-salesforce) - [ **Quaderno to Slack** Slack is a messaging platform for teams. Post messages, manage channels, users, reminders, and react to...](https://apiant.ai/connect/quaderno-to-slack) - [ **Quaderno to Stripe** Stripe is a payment processing platform for online businesses.](https://apiant.ai/connect/quaderno-to-stripe) - [ **Quaderno to Shopify** Shopify is a commerce platform for online stores and retail point-of-sale.](https://apiant.ai/connect/quaderno-to-shopify) - [ **Quaderno to QuickBooks Online** QuickBooks Online accounting — manage customers, invoices, bills, payments, vendors, expenses, and more via...](https://apiant.ai/connect/quaderno-to-quickbooks-online) ## More into Lettr - [ **HubSpot to Lettr** HubSpot is your all-in-one stop for all of your marketing software needs.](https://apiant.ai/connect/hubspot-to-lettr) - [ **Salesforce to Lettr** Salesforce is a leading enterprise customer relationship management (CRM) platform.](https://apiant.ai/connect/salesforce-to-lettr) - [ **Slack to Lettr** Slack is a messaging platform for teams. Post messages, manage channels, users, reminders, and react to...](https://apiant.ai/connect/slack-to-lettr) - [ **Google Sheets to Lettr** Google Sheets](https://apiant.ai/connect/google-sheets-to-lettr) - [ **Gmail to Lettr** Gmail is Google’s email service, featuring spam protection, search functions, and seamless integration with...](https://apiant.ai/connect/gmail-to-lettr) - [ **Google Calendar to Lettr** Google Calendar is a time management tool providing scheduling features, event reminders, and integration...](https://apiant.ai/connect/google-calendar-to-lettr) Questions ## Quaderno and Lettr, answered ### ### What can start an automation from Quaderno? Any of Quaderno's 3 triggers in the catalog, including New Contact, New Invoice and New Sale. Describe the moment in plain language and your agent picks the right one. ### ### What can your agent do in Lettr when something happens in Quaderno? Any of Lettr's 11 actions, including Update contact, Add audience list, Add contact and Add contact to list. Your agent maps the data both ways and tests every scenario before it ships. ### ### Can it also run from Lettr to Quaderno? Lettr has no triggers in the catalog today, so automations start in Quaderno. If you need the other direction, ask: your agent reads Lettr's API documentation and adds it. ### ### Do I have to build a connector for Quaderno or Lettr? No. Both are in the catalog with their triggers and actions. You describe the automation; your agent builds it, tests every scenario and keeps it running. ### ### Can my AI client use Quaderno and Lettr without building an automation? Yes. With your AI client connected to APIANT, ask it to do something in either app once and it runs that action on the spot. Ask for an automation and your agent builds it, tests every scenario and keeps it running. One connection covers both. ### ### What happens when something fails? Your agent works that out for you. It plans the failure paths along with the happy path, then tests every scenario before it ships. ### ### Is there a free plan? Yes. Every plan includes the agent, including free, and building from your own AI client spends no assistant credits.