Api Glossary

Browse 52 api terms defined in plain English, from the cultural dictionary of computing.

52 Api Terms

API Composition
A pattern where a service (or API gateway) queries multiple microservices and combines the results into a single response. Replaces cross-service database...
API Key vs Token
Two approaches to API authentication. API keys are long-lived, opaque strings tied to an account or project -- simple but risky if leaked (no expiration)....
API Rate Limit Header
HTTP response headers that inform API consumers about rate limit status: X-RateLimit-Limit (max requests per window), X-RateLimit-Remaining (requests left),...
API Versioning
Strategies for evolving an API without breaking existing clients. Common approaches: URL path (/v1/users, /v2/users), query parameter (?version=2), custom...
Backend for Frontend
A pattern where each frontend client (web, mobile, TV) has its own dedicated backend service that aggregates, transforms, and tailors API responses for that...
Breaking Change
A change to software that causes dependent code to stop working. Renaming a function, removing a parameter, changing a return type — anything that makes...
Composition API
A Composition API is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code...
Consume
To read and process messages from a queue or stream, or to call and use an API endpoint. A consumer pulls data from sources like Kafka topics, RabbitMQ queues,...
Content Negotiation
An HTTP mechanism where the client and server agree on the best representation of a resource. The client sends Accept headers (Accept: application/json,...
Context API
A Context API is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code easier...
Contract
A formal specification of the obligations and guarantees between software components. In Design by Contract, preconditions, postconditions, and invariants...
Contract Testing
A testing approach where API consumers and providers independently verify that they conform to a shared contract (expected request/response format). Tools like...
Data Contract
A formal agreement between data producers and consumers that defines the schema, semantics, quality expectations, SLAs, and ownership of a data asset. Like API...
Endpoint
A specific URL in a web API that accepts requests and returns responses. GET /api/users is an endpoint. Every REST API is a collection of endpoints. Every...
Fluent API
A Fluent API is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code easier...
Footgun
A feature, API, or tool that makes it easy for users to accidentally harm themselves — it's like handing someone a gun that's pointed at their foot. C's manual...
Geolocation API
A Geolocation API is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code...
GraphQL
GraphQL is a query language for APIs and a runtime for executing those queries against your data. Developed by Facebook in 2012 and open-sourced in 2015, it...
GraphQL Mutation
A GraphQL Mutation is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code...
GraphQL Query
A GraphQL Query is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code...
GraphQL Resolver
A GraphQL Resolver is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code...
GraphQL Schema
A GraphQL Schema is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code...
GraphQL Subscription
A GraphQL operation type for real-time data — clients subscribe to events and receive updates when the underlying data changes, typically over WebSocket. Like...
gRPC
A high-performance, open-source RPC framework developed by Google. Uses HTTP/2 for transport, Protocol Buffers for serialization, and supports streaming...
gRPC Streaming
A gRPC Streaming is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code...
HATEOAS
Hypermedia as the Engine of Application State — a REST constraint where API responses include hyperlinks to related actions and resources, allowing clients to...
idempotency
The property where performing an operation multiple times produces the same result as performing it once. In APIs, idempotent operations are safe to retry...
Idempotency Key
A unique token sent with an API request to ensure that retrying the same operation produces the same result without side effects. Critical for payment APIs and...
Idempotent Request
An HTTP request that produces the same result regardless of how many times it's executed. GET, PUT, DELETE, and HEAD are idempotent by design. POST is not --...
IDOR
Insecure Direct Object Reference — a vulnerability where an application exposes internal object IDs (user IDs, file names, database keys) in API endpoints...
Intersection Observer
A browser API that asynchronously observes when an element enters or exits the viewport (or another element). Replaces expensive scroll event listeners for...
JDBC
Java Database Connectivity — a standard Java API for connecting to and executing queries against relational databases. Provides a uniform interface regardless...
Mutation Observer
A browser API that watches for changes to the DOM tree — added/removed nodes, attribute changes, and text content modifications. Replaced the deprecated...
Open API
A specification for describing REST APIs in a standard, machine-readable format (formerly known as Swagger). Enables automatic documentation generation, client...
OpenAPI Generator
An open-source tool that reads an OpenAPI (Swagger) specification file and auto-generates client SDKs, server stubs, and API documentation in dozens of...
OpenAPI Specification
A language-agnostic standard for describing REST APIs in YAML or JSON format -- endpoints, parameters, request/response schemas, authentication, and examples....
Pagination
Breaking large result sets into smaller pages returned one at a time. Offset-based (page=3&per_page=20) is simple but slow for deep pages. Cursor-based...
Parameter
A named variable in a function or method declaration that acts as a placeholder for data passed in at call time. Parameters define what a function expects;...
Protocol Buffers
A language-neutral, platform-neutral binary serialization format developed by Google. Protobuf schemas (.proto files) define message structures and generate...
Rate Limiter
A mechanism that controls the rate of requests a client can make to a service within a time window. Common algorithms include token bucket, sliding window, and...
Rate Limiting
Controlling the number of requests a user or client can make to an API within a given time window, preventing abuse and ensuring fair resource allocation....
Rate Limiting Algorithm
Algorithms for controlling request rates: Token Bucket (tokens accumulate at fixed rate, each request costs a token — allows bursts), Leaky Bucket (requests...
Resize Observer
A browser API that reports changes to an element's dimensions. Unlike window resize events, ResizeObserver watches individual elements, enabling responsive...
REST
REST, or Representational State Transfer, is an architectural style for designing networked applications that use HTTP as the communication protocol. Defined...
Semantic Versioning
A versioning scheme (MAJOR.MINOR.PATCH) where MAJOR indicates breaking changes, MINOR adds backwards-compatible features, and PATCH fixes bugs. Enables...
Software Development Kit
A bundled collection of libraries, tools, documentation, code samples, and APIs provided by a platform vendor to enable developers to build applications for...
Structured Output
Constraining an LLM's output to conform to a specific format like JSON Schema, XML, or a grammar. Achieved through guided decoding (constraining token...
Swagger
The original name (now OpenAPI) for a specification and toolset for describing RESTful APIs in a machine-readable format, enabling auto-generated...
tRPC
A framework for building end-to-end typesafe APIs in TypeScript without code generation or schemas. tRPC lets you define API procedures on the server and call...
Webhook
A webhook is an HTTP callback mechanism that allows one system to send real-time notifications to another when a specific event occurs. Instead of the...
Webhook Retry
The retry policy used when a webhook delivery fails (non-2xx response or timeout). Good implementations use exponential backoff (e.g., 1min, 5min, 30min, 2hr,...
Webhook Secret
A shared secret used to verify that incoming webhook payloads actually come from the expected sender, typically via HMAC signature. Without it, anyone could...

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