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Use this plain-language glossary whenever a term in the documentation is unfamiliar.

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API and web terms

An Application Programming Interface is a defined way for software systems to communicate. Your application sends a request; the API returns a response.
The shared beginning of API addresses. LLM.kiwi uses https://api.llm.kiwi/v1.
A specific API function and path. For example, POST /v1/chat/completions creates a chat completion, while GET /v1/models lists models.
The action associated with a request. GET retrieves information. POST sends data for processing.
Metadata sent with a request. The Authorization header carries the API key, and Content-Type tells the API that the request body is JSON.
Data sent with a request. For a chat completion, the JSON body contains fields such as model and messages.
JavaScript Object Notation is a text format for structured data. JSON uses double-quoted keys and values, objects in braces, and arrays in brackets.
A number describing the result. 200 means success, 400 means the request is invalid, 401 means authentication failed, and 429 means a rate limit was reached.
The maximum time a client waits for a request. A timeout prevents an application from waiting forever when a network or service problem occurs.

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Authentication terms

A secret value identifying authorized API access. LLM.kiwi keys begin with sk_kiwi_. Treat a key like a password and keep it on a trusted server.
The authentication format used in the request header: Authorization: Bearer YOUR_API_KEY. The space after Bearer is required.
A value supplied to a program by its operating environment instead of being written directly in source code. It is the normal place to load an API key, though deployment access controls still matter.
Disable an API key so it can no longer be used. Revoke a key immediately if it was exposed.

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AI terms

A large language model is an AI model trained to process and generate language. It predicts output based on the instructions and context in a request.
The AI system selected for a request. LLM.kiwi documents auto for automatic selection and hrllm for Croatian-focused generation.
The input and instructions given to a model. In chat completions, this usually means the complete messages array, not only the newest user message.
A message with role system that describes the assistant’s behavior or task. It guides output but does not replace application-level security or validation.
A unit a model uses to process text. A token may be a whole word, part of a word, punctuation, or whitespace. The count varies by language, text, and tokenizer.
The maximum token capacity available for input and output in a request. When a request is too large, your application must shorten, remove, split, or summarize content.
A sampling setting that can affect output variation when supported by the selected model. Exact behavior and allowed values can differ between models.
Text generated by the model in response to the request. In a chat completion, the main result is usually at choices[0].message.content.
A response field describing why generation ended. stop commonly indicates a normal end; length commonly means an output or context limit was reached.
Receiving a response incrementally as it is generated instead of waiting for one complete response.
A confident-looking but incorrect or unsupported model output. Verify important facts and validate outputs before acting on them.

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Application terms

A software package that wraps HTTP requests in language-specific functions and types. LLM.kiwi can be used with compatible OpenAI clients by setting a custom base URL.
A restriction on request frequency or capacity. When reached, an API commonly responds with status 429.
A retry strategy that increases the wait after each temporary failure, for example one second, then two, then four. A small random delay helps prevent many clients from retrying together.
An API that does not remember prior requests automatically. For a continuing conversation, your application sends the relevant message history each time.
Code that runs in infrastructure you control and can safely access secrets. Browser JavaScript is client-side and must not contain private API keys.

Learn these concepts in context

The core concepts guide connects these terms into one complete request flow.
Last modified on July 28, 2026