FastBill Destination

Nexla's bi-directional connectors allow data to flow both to and from any location, making it simple to create a FlexFlow data flow that sends data to a FastBill location.

FastBill

Create a FastBill Destination

1. Click the + icon on the Nexset that will be sent to the FastBill destination, and select the Send to Destination option from the menu.

2. Select the FastBill connector from the list of available destination connectors. Then, select the credential that will be used to connect to the FastBill account, and click Next; or, create a new FastBill credential for use in this flow.

3. In Nexla, FastBill destinations can be created using pre-built endpoint templates, which expedite destination setup for common FastBill API write operations. Each template is designed specifically for the corresponding FastBill service, making destination configuration easy and efficient.
   • To configure this destination using a template, follow the instructions in Configure Using a Template.

   FastBill destinations can also be configured manually, allowing you to send data to FastBill services not included in the pre-built templates or apply further customizations to exactly suit your needs.
   • To configure this destination manually, follow the instructions in Configure Manually.

Configure Using a Template

Nexla provides pre-built templates that can be used to rapidly configure destinations to send data to common FastBill API write services. Each template is designed specifically for the corresponding FastBill service, making destination setup easy and efficient.

• To configure this destination using a template, select the endpoint to which data will be sent from the Endpoint pulldown menu. Then, click on the template in the list below to expand it, and follow the instructions to configure additional endpoint settings.

Create Invoice

Creates a new outgoing invoice in your FastBill account using the invoice.create service. Use this endpoint to programmatically generate invoices from data in other systems — for example, to automatically create invoices from order data, sales records, or service completion events.

• Map the Nexset fields to the corresponding FastBill invoice fields. Required fields for invoice creation include customer ID, invoice items (with description, quantity, and unit price), and currency. Additional fields such as payment terms, due date, and invoice date can be included as available in the Nexset.
• Each record in the Nexset will result in one invoice creation call to the FastBill API. Ensure that each record contains all required invoice fields before activating the destination.
• After a successful invoice.create call, FastBill returns the newly created invoice ID in the response. You can capture this response using the Response Webhook option in manual configuration if needed for downstream tracking.

For complete information about required and optional fields for invoice creation, refer to the FastBill invoice.create documentation. Note that the FastBill Classic API does not support batch invoice creation — each record generates a separate API call.

Update Invoice

Updates an existing invoice in your FastBill account using the invoice.update service. Use this endpoint to synchronize changes to invoice data — for example, to update payment status, correct line items, or change due dates based on data from an external system.

• Each record in the Nexset must include the FastBill Invoice ID (INVOICE_ID) of the invoice to update, along with the fields to be changed. The Invoice ID is the unique numeric identifier assigned to each invoice by FastBill.
• Only the fields provided in the request body will be updated — fields not included in the payload will retain their current values in FastBill.

For complete details on updatable fields and required parameters, see the FastBill invoice.update documentation. Note that certain invoice states (e.g., already sent or paid invoices) may restrict which fields can be updated.

Delete Invoice

Deletes an invoice from your FastBill account using the invoice.delete service. Use this endpoint to remove invoices that were created in error or that need to be purged as part of a data cleanup workflow.

• Each record in the Nexset must include the FastBill Invoice ID in the Invoice ID field. This is a required parameter — the delete operation will fail if this value is missing or incorrect.

  • The Invoice ID can be obtained from the FastBill web application or retrieved using the List Invoices data source endpoint.

Invoice deletion is permanent and cannot be undone. Verify that the correct Invoice IDs are mapped to this destination before activating the data flow. For complete documentation, see the FastBill invoice.delete documentation.

Create Customer

Creates a new customer record in your FastBill account using the customer.create service. Use this endpoint to sync customer data from a CRM, e-commerce platform, or other source system into FastBill, ensuring your billing system always reflects the latest customer information.

• Map the Nexset fields to the corresponding FastBill customer fields. Commonly required fields include customer type (business or private), organization name or first/last name, email address, and billing address details.
• Each record in the Nexset will result in one customer creation call. Ensure that Nexset records contain unique customers to avoid creating duplicates in FastBill.

For complete information about required and optional fields for customer creation, see the FastBill customer.create documentation.

Update Customer

Updates an existing customer record in your FastBill account using the customer.update service. Use this endpoint to keep FastBill customer data in sync with changes made in a CRM or other authoritative source system.

• Each record in the Nexset must include the FastBill Customer ID (CUSTOMER_ID) of the customer to update, along with the fields to be changed.
• Only the fields provided in the request will be updated — fields not included will retain their current values in FastBill.

For complete details on updatable fields, see the FastBill customer.update documentation.

Delete Customer

Deletes a customer record from your FastBill account using the customer.delete service. Use this endpoint to remove customers as part of data governance workflows or when decommissioning accounts.

• Each record in the Nexset must include the FastBill Customer ID in the Customer ID field. This is a required parameter.

  • The Customer ID can be found in the FastBill web application or obtained using the Get Customer data source endpoint.

Customer deletion is permanent. Deleting a customer does not automatically delete associated invoices, but it may affect reporting and data consistency. For complete documentation, see the FastBill customer.delete documentation.

Create Revenue

Creates a new revenue entry in your FastBill account using the revenue.create service. Revenue entries in FastBill record income that is not associated with a standard outgoing invoice — for example, cash sales, bank transfers, or income from platforms that manage their own invoicing. Use this endpoint to sync non-invoice revenue data into FastBill for complete financial reporting.

• Map the Nexset fields to the corresponding FastBill revenue fields. Commonly required fields include customer ID, amount, currency, and date of the revenue entry.
• Each record in the Nexset will result in one revenue creation call. Ensure all mandatory fields are present in the Nexset before activating the destination.

The FastBill Classic API does not support updating or deleting revenue entries after creation. For complete information about required fields, see the FastBill revenue.create documentation.

Delete Revenue

Deletes a revenue entry from your FastBill account using the revenue.delete service. Use this endpoint to remove revenue entries that were created in error.

• Each record in the Nexset must include the FastBill Revenue ID in the Revenue ID field. This is a required parameter.

  • The Revenue ID is the unique numeric identifier assigned to each revenue entry by FastBill. It can be obtained from the FastBill web application or from the response of a prior Create Revenue call.

Revenue entry deletion is permanent. For complete documentation, see the FastBill revenue.delete documentation.

Create Recurring Invoice

Creates a new recurring invoice schedule in your FastBill account using the recurring.create service. Recurring invoices in FastBill automatically generate and send invoices to customers on a defined schedule (e.g., monthly subscriptions or retainer agreements). Use this endpoint to programmatically set up recurring billing for customers onboarded through an external system.

• Map the Nexset fields to the corresponding FastBill recurring invoice fields. Required fields include customer ID, invoice items, recurrence frequency (e.g., monthly, quarterly), and start date.
• Each record in the Nexset will result in one recurring invoice schedule being created in FastBill.

For complete information about required fields and available recurrence options, see the FastBill recurring.create documentation.

Update Recurring Invoice

Updates an existing recurring invoice schedule in your FastBill account using the recurring.update service. Use this endpoint to modify billing schedules when subscription terms change — for example, to update pricing, adjust the billing frequency, or change the end date of a recurring billing arrangement.

• Each record in the Nexset must include the FastBill Recurring Invoice ID of the schedule to update, along with the fields to be changed.
• Only the fields provided in the request will be updated.

For complete details on updatable fields, see the FastBill recurring.update documentation.

Delete Recurring Invoice

Deletes a recurring invoice schedule from your FastBill account using the recurring.delete service. Use this endpoint to cancel recurring billing arrangements when subscriptions are terminated or customers churn.

• Each record in the Nexset must include the FastBill Recurring Invoice ID in the Recurring Invoice ID field. This is a required parameter.

  • The Recurring Invoice ID is the unique identifier assigned to the recurring schedule in FastBill. It can be obtained from the FastBill web application.

Deleting a recurring invoice schedule stops all future invoice generation for that schedule. Previously generated invoices are not affected. For complete documentation, see the FastBill recurring.delete documentation.

Create Estimate

Creates a new estimate (quote) in your FastBill account using the estimate.create service. Estimates in FastBill are pre-invoice documents sent to customers for approval before work begins. Use this endpoint to automatically generate estimates from proposal data, project scoping tools, or CRM opportunities.

• Map the Nexset fields to the corresponding FastBill estimate fields. Required fields typically include customer ID, line items (description, quantity, unit price), and currency.
• Each record in the Nexset will result in one estimate being created in FastBill.

For complete information about required and optional fields, see the FastBill estimate.create documentation.

Delete Estimate

Deletes an estimate from your FastBill account using the estimate.delete service. Use this endpoint to remove estimates that have expired, been rejected, or were created in error.

• Each record in the Nexset must include the FastBill Estimate ID in the Estimate ID field. This is a required parameter.

  • The Estimate ID can be found in the FastBill web application or obtained from the response of a prior Create Estimate call.

Estimate deletion is permanent. For complete documentation, see the FastBill estimate.delete documentation.

Create Expense

Creates a new expense (cost entry) in your FastBill account using the expense.create service. Use this endpoint to sync expense data from corporate card platforms, expense management tools, or ERP systems into FastBill for bookkeeping and tax reporting.

• Map the Nexset fields to the corresponding FastBill expense fields. Required fields typically include vendor/supplier name, amount, currency, and expense date.
• Each record in the Nexset will result in one expense entry being created in FastBill.

The FastBill Classic API does not support updating or deleting expense entries after creation. Verify expense data accuracy before activating this destination. For complete information about required fields, see the FastBill expense.create documentation.

Create Product (Article)

Creates a new product or article in your FastBill account using the article.create service. Products (called "articles" in FastBill) are reusable line-item templates that can be added to invoices and estimates. Use this endpoint to sync your product catalog into FastBill from an external system such as an e-commerce platform or ERP.

• Map the Nexset fields to the corresponding FastBill article fields. Required fields typically include article number, description, unit price, currency, and VAT rate.
• Each record in the Nexset will result in one article being created in FastBill.

For complete information about required and optional fields, see the FastBill article.create documentation.

Update Product (Article)

Updates an existing product or article in your FastBill account using the article.update service. Use this endpoint to keep your FastBill product catalog in sync when prices, descriptions, or VAT rates change in an external authoritative system.

• Each record in the Nexset must include the FastBill Article ID of the product to update, along with the fields to be changed.
• Only the fields provided in the request will be updated.

For complete details on updatable fields, see the FastBill article.update documentation.

Create Time Entry

Logs a new time entry in your FastBill account using the time.create service. Use this endpoint to sync time tracking data from external time-tracking tools, project management platforms, or calendar applications into FastBill for project billing and reporting.

• Map the Nexset fields to the corresponding FastBill time entry fields. Required fields typically include project ID or customer ID, date, duration or start/end times, and a description of the work performed.
• Each record in the Nexset will result in one time entry being logged in FastBill.

For complete information about required and optional fields, see the FastBill time.create documentation.

Create Project

Creates a new project in your FastBill account using the project.create service. Projects in FastBill are used to organize time entries, track billable hours, and manage project-based billing. Use this endpoint to automatically create FastBill projects when new projects are initiated in an external project management or CRM system.

• Map the Nexset fields to the corresponding FastBill project fields. Required fields typically include project name and customer ID. Optional fields may include project description, hourly rate, and budget.
• Each record in the Nexset will result in one project being created in FastBill.

For complete information about required and optional fields, see the FastBill project.create documentation.

Update Project

Updates an existing project in your FastBill account using the project.update service. Use this endpoint to sync project changes from an external project management tool — for example, to update project status, budgets, or hourly rates when they change in the source system.

• Each record in the Nexset must include the FastBill Project ID of the project to update, along with the fields to be changed.
• Only the fields provided in the request will be updated.

For complete details on updatable fields, see the FastBill project.update documentation.

Configure Manually

FastBill destinations can be manually configured to send data to any valid FastBill Classic API write service.

Using manual configuration, you can also configure Nexla to automatically send the response received from the FastBill API after each call to a new Nexla webhook data source — for example, to capture the IDs assigned to newly created records.

API Method

1. To manually configure this destination, select the Advanced tab at the top of the configuration screen.

2. Select POST from the Method pulldown menu. All FastBill Classic API calls — including create, update, and delete operations — use the HTTP POST method. The specific operation is determined by the SERVICE field in the JSON request body.

Data Format

3. Select JSON from the Content Format pulldown menu. The FastBill Classic API accepts only JSON-formatted request bodies. Nexla will automatically serialize the Nexset data into JSON for each API call.

API Endpoint URL

4. Enter the FastBill Classic API base URL in the URL field:

   https://my.fastbill.com/api/1.0/api.php

   All FastBill Classic API write operations are performed by POSTing a JSON body to this single URL. The SERVICE field in the body specifies which operation to perform (e.g., invoice.create, customer.update, expense.create).

Request Headers

Optional

• If Nexla should include any additional request headers in API calls to this destination, enter the headers & corresponding values as comma-separated pairs in the Request Headers field (e.g., header1:value1,header2:value2).

  You do not need to include any headers already present in the credentials. The FastBill connector handles HTTP Basic Authentication and the Content-Type: application/json header automatically.

Exclude Attributes from the Call

Optional

• If any record attributes in the Nexset should be omitted when sending data to this FastBill destination, select the attributes from the Exclude Attributes pulldown menu.

• Any number of attributes can be selected for exclusion, and all excluded attributes will be shown in the field. To remove an attribute from the list, click the X icon next to the attribute name.

Record Batching

Optional

1. If records should be sent to this destination in batched API calls, check the box next to Would you like to batch your records together? to enable record batching.

2. Enter the maximum number of records that should be batched together in a single API call in the Batch Size field. By default, this value is set to 100.

3. Select the algorithm that will be used to group records into batches from the Grouping Algorithm pulldown menu. The sample request shown in the panel on the right will be updated to reflect the current batching settings.

The FastBill Classic API processes one service call per request. If batching is enabled, ensure that the grouping algorithm and request body structure are compatible with how the target FastBill service expects to receive data.

Response Webhook

Optional

Nexla can automatically send the response received from the FastBill API after each call to a new Nexla webhook data source. This option allows you to keep track of the status of each API call and capture any additional information returned, such as newly assigned FastBill record IDs.

• To enable this option, check the box next to Would you like to process the API response as a Nexla Webhook source?.

Sample Request Payload

Sample request payloads containing a portion of the Nexset data that will be sent to the FastBill API endpoint based on the current settings are shown in the Sample Payload panel on the right. These samples can be referenced to ensure that the destination and request settings are correctly configured.

• Click on a sample request payload to expand it and view the complete payload content.
• Sample payloads are automatically updated with each setting change, making it easy to verify that changes achieve the desired effect.

Endpoint Testing (Manual Configuration)

After all endpoint settings have been configured, Nexla can send a test payload to the FastBill API to ensure that the destination is configured correctly.

1. To send a test payload, select the Test button at the top of the Sample Payload panel, and click on a listed sample payload to expand it.

2. If any modifications to the sample payload are needed, make the necessary changes directly within the sample window.

3. Click the Send Test Data button at the top of a sample payload to send the test payload to the FastBill API using the current settings.

Save & Activate the Destination

• Once all endpoint settings have been configured, click the Done button in the upper right corner of the screen to save and create the destination. To begin sending data to FastBill, open the destination resource menu, and select Activate.

  The Nexset data will not be sent to FastBill until the destination is activated. Destinations can be activated immediately or at a later time, providing full control over data movement.