Developer-friendly API
Backend integrations depend on predictable requests, responses and failure handling. Cardflo exposes RESTful payment endpoints with typed JSON structures, standardised error codes, idempotency keys and consistent rate-limiting headers through one integration path.
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Software engineers integrating multiple acquirer partners face fragmented technical documentation, inconsistent request structures, and conflicting error logic. Building a unified routing layer from scratch requires backend teams to map legacy XML protocols against modern JSON payloads, consuming engineering resources that should be allocated to core product development rather than standardising disparate gateway responses.
Cardflo abstracts these complexities by exposing unified restful payment endpoints and strictly typed JSON payloads. The orchestration layer standardises responses across the entire acquirer partner network, allowing backend developers to manage idempotency, parse granular HTTP status codes, and maintain consistent rate limiting rules through a single integration path.
The developer-friendly API, complete with SDKs and clear documentation, significantly cuts down integration time and development complexity. This allows teams to launch new payment functionalities faster, accelerating time to market.
Developer-friendly API overview
The technical foundation of any scalable orchestration integration relies on predictable data structures and logical resource URIs. Software engineers require immediate visibility into request formats, HTTP method applications, and error code translations to construct resilient server-side architectures.
Cardflo normalises interactions with global acquirer partners into a single technical standard, exposing restful payment endpoints that accept and return strictly validated JSON. This standardisation extends to consistent idempotency key usage to prevent duplicate charges during network timeouts, alongside predictable rate limiting headers that inform backend throttling logic.
While developers can configure event listeners separately by referencing the webhooks documentation, the core API dictates the synchronous request and response flow required to initiate transactions, capture funds, and query gateway state.
By mapping dozens of proprietary acquirer specifications into one unified dictionary, engineering teams avoid maintaining custom translation layers for every new market expansion or local payment method.
How developer-friendly API works
Constructing the JSON payload
Backend applications compile the transaction data into a strictly validated JSON structure containing the merchant identifier, currency, amount, and payment method details. Engineers submit this payload to the designated restful payment endpoints, ensuring that variable types exactly match the published schema to prevent immediate validation rejections before the request even reaches the orchestration engine.
Managing idempotency and retries
Every POST request requires a unique idempotency key included in the HTTP header. If a network timeout occurs and the backend system retries the same payload, the orchestration layer recognises the key and prevents duplicate processing. The API immediately returns the cached original response, protecting the merchant from initiating unintended multiple charges against a consumer account.
Parsing standardised error codes
Upon completion or failure, the API returns a unified JSON object containing HTTP status classifications and granular internal error codes. Instead of handling thirty different proprietary decline messages from various acquirer partners, backend algorithms read one consistent code array. This allows software engineers to program precise fallback logic, automatic retries, or clear user-facing checkout errors.
Why developer-friendly API matters
Reducing technical debt
Maintaining separate codebases for multiple acquirer integrations forces engineers to continuously patch brittle XML translators and custom error mappers. By standardising all outbound and inbound data through restful payment endpoints, software teams write integration logic once. This unified approach eliminates legacy codebase clutter and significantly reduces the technical debt associated with scaling global payment operations.
Accelerating new market entry
When a merchant needs to route transactions to a new geographic region, engineering teams do not have to study a new proprietary technical specification. Because the JSON payload structure remains identical regardless of the underlying acquirer partner, backend applications only require minor configuration adjustments to support additional currencies or alternative local methods.
Regulatory notes for developer-friendly API
Normalised PSD2 challenge fields
European PSD2 regulations mandate Strong Customer Authentication for digital transactions, requiring specific data fields to support 3D Secure challenges. The API schema mandates these fields for applicable regions, ensuring that backend applications construct payloads containing the necessary browser fingerprints, IP addresses, and customer device information.
By standardising these parameters within the JSON object, developers can pass authentication requirements through the restful payment endpoints to any regulated acquirer partner. The API normalises the step-up challenge URLs returned by the issuer, allowing the merchant application to handle frictionless and challenge flows consistently.
PCI DSS data transmission standards
To comply with PCI DSS requirements regarding the transmission of sensitive cardholder data, the orchestration API strictly mandates Transport Layer Security (TLS) 1.2 or higher.
Any request originating from a server negotiating a lower encryption protocol is immediately rejected with a standard 403 Forbidden status code.
Furthermore, engineers must ensure that raw Primary Account Numbers and security codes are never logged within their own backend diagnostic tools when constructing the JSON request. The API responses are deliberately engineered to return truncated PANs and network tokens to protect downstream merchant database compliance.
Developer-friendly API use cases
Typed JSON payment resources
Backend engineers integrating card payment flows need predictable JSON schemas for payment creation, capture, refund and status retrieval without writing separate parsers for each operation. Cardflo provides RESTful payment endpoints with consistent resource naming, field types and response structures, reducing integration-specific transformation logic.
Idempotent payment retries
Checkout services may repeat a payment creation request when an HTTP timeout leaves the original authorisation result unknown, risking duplicate charges. Cardflo accepts idempotency keys on eligible write requests and returns the corresponding result for recognised retries, allowing engineers to implement controlled recovery without creating another payment.
Standardised API error handling
Payment applications must distinguish malformed JSON, failed validation, unavailable resources and declined authorisations so each outcome follows the correct recovery path. Cardflo returns standard HTTP statuses and structured error codes, enabling backend services to map retryable faults, developer corrections and customer-facing payment failures to separate handling rules.
Rate limited transaction queries
Finance and operations applications can generate bursts of transaction status queries during reconciliation runs, causing requests to exceed published API rate limits. Cardflo exposes predictable limit responses and pagination controls so engineers can apply backoff, pace concurrent calls and resume data retrieval without repeatedly requesting the same result set.
Developer-friendly API by the numbers
Typical efficiency gains reported by engineering teams when switching from legacy SOAP interfaces to modern RESTful APIs with comprehensive SDKs.
The standard industry benchmark for gateway overhead per request, excluding downstream latency introduced by the card networks and issuing banks.
The observed reliability rate for preventing duplicate transactions in high-volume environments where network retries are common.
Methodology: these figures are illustrative ranges drawn from published industry data and observed merchant cohorts, not guarantees. Actual results depend on your risk profile, card mix, geography and acquiring setup, and are confirmed only in your own pricing and approval terms.
Related terms
Talk to our team about a live rollout across our acquirer partners' rails.
What you get with Developer-friendly API
- Strictly typed JSON requests and responses eliminate the need to parse legacy XML formats from individual acquirer partners.
- Predictable restful payment endpoints align with standard HTTP verbs for creating, reading, updating, and deleting transaction records.
- Universal idempotency keys prevent duplicate transaction execution during backend retry mechanisms or unexpected network latency.
- Standardised HTTP error mapping normalises proprietary acquirer decline codes into a single, predictable JSON response dictionary.
- Explicit rate limiting headers return current usage quotas to help backend applications throttle requests algorithmically.
- Pagination controls allow engineers to retrieve large datasets of historical transactions with offset and limit parameters.
A short scoping call, then a written plan for your MIDs.
Questions about Developer-friendly API
How does the API enforce idempotency for transaction requests?
Engineers must include an Idempotency-Key header with every POST request directed at the restful payment endpoints. The orchestration layer stores this unique string alongside the exact JSON request body for twenty-four hours.
If the server receives an identical request with a matching key within that window, it bypasses the acquirer partner network entirely and returns the cached HTTP response.
This mechanism acts as a critical failsafe when network timeouts force backend applications to automatically retry a transaction that may have already succeeded.
What format does the orchestration layer use for API responses?
All responses are formatted as strictly typed JSON, regardless of the upstream data format required by the executing acquirer partner. The API standardises every field, ensuring that integers, booleans, and strings appear predictably.
If an acquirer partner returns a proprietary XML decline message, the orchestration engine translates this into a standard HTTP 400-level status code paired with a unified internal error identifier. This allows software teams to parse responses using standard libraries without maintaining custom string manipulation logic.
How are rate limits communicated to integrating backend applications?
The API includes standard HTTP headers in every response to inform the backend application of its current consumption status. These headers detail the maximum number of permitted requests per minute, the remaining quota, and the exact timestamp when the limit resets.
If an application exceeds the defined threshold, the server returns a 429 Too Many Requests status code. Software engineers can use these header values to program automatic throttling algorithms and exponential backoff mechanisms to ensure continuous availability.
How should developers handle partial updates to existing resources?
Software engineers use the HTTP PATCH method to modify specific fields on an existing entity, such as updating metadata on a stored customer record, without overwriting the entire object. The JSON payload only needs to contain the key-value pairs targeted for modification.
The API validates these partial inputs against the schema and returns the fully updated resource. This approach minimises payload size and prevents unintended data erasure that can occur when using a standard PUT request.
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