APIs and web services represent different scopes of software communication. An API defines any contract between software components, whether local function calls, operating system interfaces, or network requests.

A web service is a specific type of API that operates over networks using protocols like HTTP or SOAP. This hierarchical relationship means all web services are APIs, but many APIs never touch a network. Understanding this distinction affects your architecture decisions, performance expectations, and integration strategies.

In Brief:

• APIs are broad software interfaces for any component communication, local or remote
• Web services are network-specific APIs that operate over HTTP, SOAP, or similar protocols
• All web services are APIs, but many APIs never touch a network
• Choose APIs for local, high-performance interactions; choose web services for cross-platform integration

Comparing APIs vs Web Services

Here’s a table that lists the differences between these concepts:

Comparison Table: Differences Between API and Web Services

APIs are the umbrella concept, while web services occupy the corner devoted to networked communication.

What They Are

Think of an API as any doorway between software components—sometimes it's a local function call, other times it's an HTTP request. A web service narrows that definition to doors you can only reach over a network. Every web service is an API, but plenty of APIs never leave the host machine.

The SQLite C API lets you query a local database without a single network packet, whereas a cloud database's REST endpoint is a classic web service. For example, calling sqlite3_open("mydb.db", &db) executes entirely on the local machine, while fetch('https://api.mongodb.com/v1/databases') traverses the internet.

This scope difference shapes architecture: if your modules run in the same process, a local API avoids network latency; if they're distributed, a web service becomes unavoidable.

Protocol Requirements

APIs have no allegiance to a particular protocol. You might call a POSIX function, open a WebSocket, or send a gRPC message—whatever fits the job. Web services rely on network protocols such as HTTP, HTTPS, or even SMTP. Traditional SOAP services wrap XML envelopes inside HTTP POSTs, while modern REST services map HTTP verbs (GET, POST, PUT, DELETE) to resources.

Non-network APIs—say, DirectX on Windows—highlight this split: they expose powerful capabilities yet never cross the network boundary. Consider ID3D11Device::CreateTexture2D() which allocates GPU memory locally, versus an AWS S3 PUT request that uploads an image to a remote server.

The protocol flexibility of general APIs lets you mix local and remote interactions, but web services lock you into network semantics, influencing how you handle time-outs, retries, and security.

Data Format Flexibility

With APIs, you choose the payload. JSON is popular for readability, binary formats like Protocol Buffers win on speed, and some legacy SDKs still pass plain structs. Web services typically standardize on a smaller palette.

SOAP mandates verbose XML, which boosts schema validation but inflates payload size. RESTful services lean toward JSON, trimming overhead and making responses friendlier to JavaScript clients.

A local Node.js API might pass JavaScript objects directly: database.findUser({id: 1234}), while its web service equivalent requires serialization: await fetch('/api/users/1234').then(res => res.json()).

The lighter weight of JSON improves bandwidth usage, especially on mobile links, whereas XML's strict schemas appeal to industries that need airtight validation. Your format decision balances performance against contractual rigor.

Implementation Complexity

Standing up a local API can be as simple as exporting a function. A web service demands more: a web server, routing, authentication, error handling, and often documentation like WSDL or OpenAPI. You'll configure CORS, manage TLS certificates, and monitor network latency—overhead that doesn't exist when both caller and callee share the same memory space.

Consider implementing a payment processor: a local API might be PaymentEngine.processPayment(cart, creditCard), while a web service implementation requires handling request validation, authentication tokens, and network failures:

1try {
2  await axios.post(
3    "/api/payments",
4    { cart, token },
5    { headers: { Authorization: "Bearer xyz" } },
6  );
7} catch (error) {
8  /* retry logic */
9}

Maintenance follows suit: updating a DLL is trivial compared to versioning a public endpoint that external partners rely on. For internal modules where speed and simplicity matter, a non-network API keeps complexity down; for cross-platform ecosystems, the heavier lift of a web service buys you reach and interoperability.

Real-World Examples of APIs and Web Services

Understanding the distinction becomes clearer when you see how APIs and web services function in actual development scenarios.

API Examples:

• Local APIs - SQLite database driver, DirectX graphics API, POSIX file system calls
• Library APIs - Stripe SDK methods, React hooks, JavaScript fetch API
• Operating System APIs - iOS camera access, Android location services, Windows registry functions

Web Service Examples:

• SOAP Web Services - UPS shipping calculations, banking transaction processing, government data exchanges
• REST Web Services - Twitter API, GitHub repository management, Stripe payment processing
• GraphQL Web Services - GitHub GraphQL API, Shopify storefront API, content delivery networks

This distinction helps clarify the scope difference: APIs can operate entirely within your application, while web services always require network communication and standardized protocols.

What Is an API?

An Application Programming Interface (API) is a software intermediary that lets two pieces of software exchange data or functionality through a defined set of rules — a contract that spells out allowed requests, required parameters, and expected responses.

Unlike web services, an API can live entirely inside your application, across a local network, or on the public internet.

Think of the contract as a handshake: you expose only the inputs and outputs, never the implementation. That separation lets you refactor or scale internals without breaking callers. You'll encounter APIs everywhere, from your operating system's file functions to third-party payment gateways.

You'll meet several flavors in day-to-day work:

• Library APIs: in-process calls packaged with a language runtime or third-party SDK
• Operating system APIs: system calls that manage files, memory, or hardware
• Database APIs: query engines, drivers, and ORMs that abstract persistence
• Web APIs: HTTP endpoints a remote client can hit for data or services

Modern implementations add more nuance. RESTful endpoints deliver JSON over HTTP, GraphQL lets the client shape the payload, and gRPC compacts messages with Protocol Buffers for high-throughput microservices.

Regardless of style, each API hides complexity behind predictable inputs and outputs. That abstraction is the backbone of modular architectures and the reason microservices can update independently without grinding your release cycle to a halt.

Good APIs live or die by their docs and versioning strategy. Clear OpenAPI specs, semantic version numbers, and deprecation timelines keep teams aligned and integrations stable.

What Is a Web Service?

A web service exposes application functionality over a network using standard protocols. It's a specialized API designed for machine-to-machine communication across HTTP, HTTPS, SMTP, or similar transport layers.

Every call travels through the network, making web services inherently distributed and platform-independent. This network requirement separates web services from broader APIs, where local, in-process calls are perfectly valid.

Three architectural styles dominate modern web services. SOAP (Simple Object Access Protocol) uses XML envelopes, strict schemas, and formal contracts described in WSDL files.

The trade-off for complexity is enterprise-grade reliability, built-in WS-Security, and detailed error handling—features that still power banking and government integrations according to Testsigma research.

REST (Representational State Transfer) takes a different approach. It models resources rather than actions, embraces stateless requests, and prefers lightweight payloads—usually JSON, occasionally XML. Statelessness means any server can handle a request without remembering previous calls, making horizontal scaling straightforward.

REST endpoints are typically documented with OpenAPI (formerly Swagger), turning service discovery into a single JSON or YAML file according to Integrate.io documentation.

GraphQL exposes a single endpoint backed by a strongly-typed schema. Clients query exactly the fields they need, reducing over-fetching problems common in REST.

While not as protocol-heavy as SOAP or as widely adopted as REST, GraphQL's flexible query model is gaining traction in microservices and headless CMS ecosystems.

Every web service requires governance: versioning, authentication, authorization, and performance monitoring. SOAP relies on WS-Security and message-level policies; REST and GraphQL typically use HTTPS with token-based schemes like OAuth2.

Because each request crosses the network, you must account for latency, error handling, and graceful degradation—trade-offs that come with seamless integration across disparate platforms.

When to Use APIs vs Web Services

The choice between APIs and web services depends on your architecture requirements, performance needs, and integration scope.

Choose APIs When

You're working inside a single application or on the same machine where speed matters more than reach. Since the interface doesn't travel over a network, you can call functions directly, eliminating latency and network failure points.

A mobile app talking to a local SQLite database through a native library exemplifies this—the entire exchange happens in-process, so bandwidth limits don't slow you down.

The same applies to operating-system calls like file I/O or camera access. These interfaces work entirely offline, use any protocol, and serialize data in formats optimized for performance, including binary structures. This flexibility reduces infrastructure overhead: no web server, SSL certificate, or service registry to maintain.

The trade-off is scope. A purely local interface is tightly coupled to its host application, so exposing it to other platforms later means a rewrite or adapter layer. If your use case is bounded, latency-sensitive, and under your control, stick with a local approach and keep moving parts to a minimum.

Choose Web Services When

You need components on different networks—or built with different tech stacks—to communicate as equals. Web services cross that boundary using standardized web protocols like HTTP, SOAP, or REST, making language and platform differences irrelevant.

When your accounting system in Java must send invoices to a supplier's .NET portal, a SOAP service with shared WSDL gets both sides speaking the same dialect.

Web services excel in service-oriented or microservices architectures where each service can scale independently behind a load balancer.

They also carry enterprise benefits: SOAP offers built-in WS-Security and strict XML schemas that regulated industries rely on, while RESTful services provide statelessness for horizontal scaling.

The price is complexity—network hops introduce latency, payloads (especially XML) add weight, and you'll juggle concerns like versioning, discovery, and retries.

Choose a web service when interoperability, loose coupling, and external consumption outweigh the overhead, such as public interfaces for partners, B2B integrations, or any system expected to evolve without forcing every client to upgrade in lockstep.

How Strapi Supports Both APIs and Web Services

Strapi automatically generates REST endpoints for every Content-Type you create. GraphQL endpoints are also available, but require the installation and configuration of the GraphQL plugin. These endpoints operate as APIs whether accessed locally or over a network.

Your REST endpoints map to familiar CRUD operations, while the GraphQL schema lets clients request specific fields. Both approaches abstract your database logic behind a clean interface. When your frontend runs on the same server, you're using a local API.

For example, a typical REST interaction with Strapi might look like:

1// Fetching articles using Strapi's REST API
2fetch('http://localhost:1337/api/articles')
3  .then(response => response.json())
4  .then(data => {
5    console.log('Articles:', data.data);
6    // Process your articles here
7  })
8  .catch(error => console.error('Error fetching articles:', error));

While the equivalent GraphQL query demonstrates field selection:

1// Fetching only the title and author fields from articles
2// Fetching only the title and author fields from articles
3fetch('http://localhost:1337/graphql', {
4  method: 'POST',
5  headers: {
6    'Content-Type': 'application/json',
7  },
8  body: JSON.stringify({
9    query: `
10      {
11        articles {
12          documentId
13          title
14          author {
15            documentId
16            name
17          }
18        }
19      }
20    `
21  }),
22})
23  .then(response => response.json())
24  .then(result => console.log('GraphQL result:', result.data.articles));

Deploy that frontend elsewhere, and those same endpoints become network-accessible web services that communicate over HTTP.

This flexibility matters for architectural decisions. Keep endpoints local for tight coupling with server-side rendering, or expose them publicly for third-party integrations. The same generated code handles both scenarios—you choose the consumption pattern.

Security scales with your architecture. Enable authentication middleware and tokens protect your routes whether they run on localhost or in production. Deploy behind a load balancer and each request stays stateless, so any node can handle it. This stateless approach supports horizontal scaling as your system grows.

When you move toward microservices, Strapi's endpoints integrate like any other service. They publish clear contracts, accept JSON by default, and stay decoupled from client technology. Scale becomes a deployment question—Strapi Cloud or any container platform can host the same REST and GraphQL services with autoscaling infrastructure.

Making the Right Integration Choice

The differences between API and web service shapes how you architect software systems. An API defines a general contract for software interaction, while a web service delivers that contract over a network using protocols like HTTP or SOAP.

Web services require network access by definition, making every web service an API—but many APIs operate entirely within local systems.

Choose local APIs for lean, low-latency interactions. Choose web services for cross-platform, partner-facing scenarios where standards-driven protocols benefit interoperability. Strapi generates REST and GraphQL endpoints that work both locally and over networks, letting you evolve from simple API calls to full web services without changing your data model.

Evaluate your latency, interoperability, and infrastructure requirements before committing to either approach.

Strapi automatically generates both REST and GraphQL endpoints, letting you choose the right approach without rebuilding your backend. Whether you need local APIs or network-accessible web services, get production-ready endpoints in minutes.

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