Inference
Chat Completions API
OpenAI's original chat endpoint, POST /chat/completions, which takes an array of role-tagged messages (developer or system, user, assistant, tool) and returns one or more completion choices.
In depth
OpenAI's original chat endpoint, POST /chat/completions, which takes an array of role-tagged messages (developer or system, user, assistant, tool) and returns one or more completion choices. The client manages conversation state by resending the message history on every request. Its request shape became a de facto standard that many other providers, gateways, and local inference servers expose as an OpenAI-compatible API. OpenAI still supports it but recommends the Responses API for new projects.
Primary source: developers.openai.com
Example
In practice, developers reach for Chat Completions API when they need the capability described above as part of an AI feature or workflow.
Go deeper at Developers Digest
Hands-on guides, comparisons, and tutorials that cover Inference.
FAQ
Common questions
What is Chat Completions API?
OpenAI's original chat endpoint, POST /chat/completions, which takes an array of role-tagged messages (developer or system, user, assistant, tool) and returns one or more completion choices.
Why does Chat Completions API matter for AI developers?
Chat Completions API sits in the Inference part of the AI stack. Understanding it helps you make better decisions when building, debugging, and shipping AI features.
Where can I learn more about Chat Completions API?
Developers Digest publishes tutorials and videos that cover Inference topics including Chat Completions API. Check the blog and YouTube channel for hands-on walkthroughs.
Related
Related terms
Inference
Constrained Decoding
A generation technique that restricts which tokens a model may pick at each step so the output is guaranteed to match a format such as a regular expression, a grammar, or a JSON Schema.
Inference
Cross-Entropy Loss
The standard loss function for classification and language model training, measuring how much probability the model gave to the correct answer.
Inference
Context Engineering
The discipline of designing what information goes into a model's context window and how it is structured.
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