Sandbox Walkthrough

Overview

Welcome to the Newline Sandbox! Here we’ll show you how to build against the Newline API using the main features and admin tooling available in the Newline Sandbox.

Please note that the Newline Sandbox does not contain all of the features available in our Production environment. For clients interested in immediate access with a limited number of accounts, please reach out to your Relationship team.

Constraints

While the Sandbox will afford the Client's opportunities to test key payments scenarios, the following features will be excluded and handled by our engineering teams

Creation of Customers - any customer staged are business customers, with only name and address populated.
Creation of general Synthetic Accounts - Any general Synthetic Accounts staged are master accounts with 1:1 relationships established to a Custodial Account; in addition, this Custodial Account represents a Commercial DDA. The staged Synthetic Accounts will have varying balances.

Sandbox vs. Production, environment differences

The Newline Sandbox endpoints enable clients to stage outcomes and interactions that are not available in production. The table below outlines some of the key differences between the sandbox and production environments.

API availability

Endpoint	Sandbox	Production
Synthetic Accounts	When creating a Synthetic Account of type `ach_external`, `wire_external`, `instant_payments_external`, no authentication is performed. The external account information provided will not initiate a connection to a financial institution.	When creating a Synthetic Account of type `ach_external`, `wire_external`, `instant_payments_external`, a valid account and routing number is required. The external account connection will be used to transfer funds to/from a financial institution.
Transfers	Transfers to and from external accounts will be simulated. No real money movement will occur.	Transfer limits (frequency and volume) may exist based on the rules of your Program (e.g., 20 daily external transfers, a total daily $10,000 transfer limit). This will be discussed during Program onboarding.
Mock Transactions	Transaction auto-generation exists to validate how externally originated transactions render on your application. These can be auto-generated using a Sandbox specific endpoint.	Unavailable in production.
Virtual Reference Numbers (VRNs)	VRNs can be created off of any of the staged, `general` Synthetic Accounts.	Not currently in production (`beta` access only)
Debit Cards	Debit Card interactions can be tested in Sandbox, all of which are simulated. No real card activity or payments will occur.	Not currently in production (`beta` access only)

Sandbox CSV Reporting

Enable CSV reporting in Sandbox to validate file delivery and reporting integrations before moving to Production. Coordinate enablement with your Newline Specialist during implementation.

The Managed File Transfer (MFT) onboarding checklist documents the same configuration steps, delivery behavior, and validation process for Sandbox and Production, with separate setup for each environment.

Authorizations CSVs Explained and Posted Transactions also document consistent file structure, delivery cadence, and header-only behavior across environments for those reports. Their availability remains subject to feature enablement and program configuration.

Sandbox uses synthetic activity rather than live payments. Report availability, included columns, and field population depend on your program configuration and enabled features, so files may differ between environments when those configurations differ. See Program Level Configuration Flags for details.

Sterling Setup Requirements

Sandbox CSV delivery requires the same Managed File Transfer (MFT) setup process used for Production. Configure each environment separately.

Coordinate Sandbox reporting and MFT setup with your Newline Specialist during implementation.
Complete the delivery configuration, including a Sterling MFT directory and the required connection and routing details. A Sterling directory must be configured before files can be delivered.
Confirm your reporting modes, Intraday interval, and applicable feature dependencies.
Complete onboarding and connectivity validation. CSV delivery does not begin until onboarding and setup are complete.

See the Managed File Transfer (MFT) onboarding checklist for delivery options, directory requirements, encryption preferences, and testing steps.

CSV Types Available for Testing

You can test the reports available under your Sandbox program configuration:

Reporting mode	Reports	Configuration and purpose
Intraday	Settled Transactions, Updated Transactions, Accounts	Delivered together as the core Intraday bundle at your selected interval. Use these reports for operational monitoring. Individual Intraday reports cannot be selected or excluded independently.
Intraday authorization reporting	Pending Authorizations, Denied Authorizations	Included in the Intraday bundle when VRNs, Client Authorization, and Intraday reporting are enabled. These reports are not independently configurable.
Prior Day	Settled Transactions, Updated Transactions, Accounts	Summarize prior-period transaction activity and end-of-day account balances.
Prior Day posting-aligned reporting	Posted Transactions; statement-aligned closing balances in Accounts, when enabled	Availability depends on program and environment configuration. Confirm Sandbox availability with your Newline Specialist.

Settled Transactions reports capture completed settlement events. Updated Transactions reports capture qualifying changes to existing transaction records. Posted Transactions reports reflect bank statement posting, which is separate from settlement; do not use settlement alone to infer that posting data is available.

For bundle rules and report purposes, see Understanding Intraday vs Prior Day Reporting, Authorizations CSVs Explained, and the Posted Transactions (Prior Day) CSV Guide.

Cadence, File Generation, and Empty Files

File delivery is schedule-based; transaction rows depend on qualifying lifecycle events during the reporting window. Generating test activity does not mean that every transaction report will contain a row.

Intraday: Files are generated at the configured interval, including weekends and holidays. All reports in the Intraday bundle share the same cadence.
Prior Day: Core reports are generated daily, including weekends and holidays. Posting-aligned reports and balances depend on bank posting cycles and may have different availability or delivery timing.
Header-only files: A valid empty CSV contains column headers and no data rows. This indicates successful generation and delivery with no qualifying records for that report's window.

Header-only files are common during low-activity Sandbox testing, when no qualifying settlement, update, posting, or authorization activity occurs. Accounts reports may also contain unchanged balances. Do not treat header-only files as delivery failures or expect every scheduled file to contain new data.

After setup is complete, investigate missing scheduled files or missing or malformed headers, rather than escalating valid header-only files. See CSV Delivery Windows & SLA Details for timing and escalation guidance.

Synthetic Activity Limitations and Validation

Sandbox lets you test reporting mechanics, but its simulated payments do not move real money or reproduce all Production activity. Interpret CSV contents according to the lifecycle events and data available in your test scenarios. Do not assume that simulated settlement produces bank statement posting data or statement-aligned closing balances.

Before moving to Production:

Verify delivery to your configured directory across at least one complete delivery cycle.
Validate file structure and expected columns for your enabled configuration using CSV Samples & Field Maps.
Confirm that your ingestion process accepts complete bundles, header-only files, and unchanged account balances.
Confirm the reporting features and separate MFT configuration required for Production with your Newline Specialist.