What is API integration?
Last reviewed 7 October 2026
API integration is the use of application programming interfaces (APIs) to connect software, so that one application can read data from, or trigger actions in, another through a documented interface. IBM describes it as using APIs to expose integration flows and connect enterprise applications, systems and workflows for the exchange of data and services. It is the usual foundation for modern integrations.
Also called: API integrations, API-based integration, REST API integration.
Why API integration matters
An API is a contract. The provider promises that a request in a set format will get a response in a set format, and usually versions that contract so it does not change without warning. Building on that contract is far more dependable than reading another system's database directly or scraping its screens, both of which break when the vendor changes internals it never promised to keep.
API integration is also what makes automation possible at scale. Once a system exposes an API, any number of workflows, agents and other applications can work with it without anyone touching its interface.
How it works
A web API exposes resources, each with an address. IBM's explainer notes that web APIs commonly use HTTP methods to act on those resources, for example GET to read and DELETE to remove. The client sends a request with credentials, the server checks them, does the work and returns a response with a status code and, usually, a JSON body.
Authentication comes first in practice. Most APIs use an API key or an OAuth token, scoped to what the client may do. A careful integration asks for the narrowest scope it needs, stores the credential outside its code and handles the token expiring.
Between two APIs sits mapping. The source returns a customer in one field layout; the target expects another. The integration renames fields, converts formats and fills defaults. It also respects limits: providers cap the number of requests per period, so integrations batch calls, back off when told to slow down and page through large result sets.
IBM separates synchronous REST APIs, where the caller waits for an answer, from asynchronous, event-based interfaces, where the provider notifies the caller later. Webhooks are the everyday example of the second kind.
Worked example: enriching a new lead
A marketing form creates a new lead in the CRM. An integration calls the CRM's API with a GET request to fetch the lead, then calls a company-data provider's API with the lead's email domain to look up company size and industry. It maps the provider's response onto two custom CRM fields and sends an update request to save them on the lead.
If the company-data API returns a rate-limit response, the integration waits the time the response asks for and tries again. If it returns nothing for the domain, the integration leaves the fields empty and tags the lead for manual review rather than guessing. Each call and its response status is logged, so when a salesperson asks why a lead has no industry, someone can see which call returned nothing.
How Swfte relates to it
Built in the product
API integration sits at the centre of how Swfte works. Studio workflows call external systems through integrations that wrap their APIs, and an API for custom systems covers anything the catalogue does not. Studio does not drive desktop screens, so it relies on the systems you connect having an API.
Connect is itself an API integration product for AI models: one OpenAI-compatible API in front of many model providers, with your own provider keys, routing and fallback, budgets and audit events. An application written against one provider's API can point at Connect and reach others without rewriting its calls.
Related terms
- Webhook
A webhook is an HTTP request that one system sends automatically to a URL you provide whenever a chosen event happens, carrying data about that event.
- Software integration
Software integration is the work of connecting separate applications so they can share data and trigger actions in each other, making them behave like parts of one system.
- iPaaS (integration platform as a service)
iPaaS, short for integration platform as a service, is a hosted set of tools for connecting applications, data sources and systems without running your own integration servers.
- Function calling
Function calling is a feature of language model APIs that lets a model return a structured request to run a function you defined, with arguments that match its schema, instead of only replying in text.
- Model Context Protocol (MCP)
The Model Context Protocol (MCP) is an open protocol that gives AI applications a standard way to connect to external tools, data sources and prompts, so one integration can work with any compatible client.
Common questions
- What is the difference between an API and an API integration?
- An API is the interface a system offers: the addresses, methods and data formats other software can use. An API integration is the working connection someone builds on top of it, including authentication, data mapping, error handling and scheduling, so two or more systems actually exchange data and actions.
- What is an example of API integration?
- A common one is an online shop calling a payment provider's API to take a card payment, then calling a shipping carrier's API to create a label. Inside a company, syncing customers between a CRM and an ERP so both hold the same record, an example IBM gives, is another everyday case.
- Is API integration secure?
- It can be when built carefully. Use HTTPS, give each integration its own credential with the narrowest scope, store secrets in a vault rather than in code, rotate them, and log calls. Validate data coming back from an API as you would any input, because a faulty upstream system can send bad data.
- How do AI agents use API integration?
- An agent calls APIs through tools: functions that wrap an API call with a description the model can read. The model decides which tool to call and with what arguments, and the platform makes the actual request. Function calling and MCP are two common ways to give a model those tools.
Sources
Definitions on this page were read on the sources below on 7 October 2026. Where sources define the term differently, the page says so. The full glossary lists more terms.
- IBM explainer on API integration (read 2026-10-07)