Skip to content
Devgo

OpenAI API

The API for GPT-4o, GPT-4o-mini, and other OpenAI models. Chat completions, function calling, vision, audio (whisper/tts), embeddings, and fine-tuning. The most popular LLM API. Pay per token. Powers most AI apps.

Created by

Sam Altman, Elon Musk, Ilya Sutskever, Greg Brockman, et al. · Co-founded OpenAI in 2015

Website
When to use
  • Most AI apps needing a capable LLM.
  • Function calling, vision, audio.
  • When you want the most popular API.
  • Prototyping quickly.
When not to
  • When cost is critical (use cheaper models or local).
  • Privacy-sensitive data (use local or self-hosted).
  • When you need a specific non-OpenAI model.

Definition

The provides access to GPT-4o, GPT-4o-mini, o1 (reasoning), embeddings (text--3), Whisper (speech-to-text), TTS (text-to-speech), DALL-E (images), and . Chat completions with messages, , vision, and structured output.

Why it exists

To provide access to state-of-the-art LLMs via a simple API, enabling developers to build AI apps without training models or managing infrastructure.

How it works

POST to api.openai.com with your API key. Messages array (system, user, assistant). Model parameter picks the model. for tool use. Streaming for real-time responses. Vision: send images. Embeddings: vector representations.

Scaling limits

Pay per token (can get expensive). Rate limits. API changes/deprecations. Data privacy (your data goes to OpenAI). Vendor lock-in to their API format.

Cost shape

Pay per token. GPT-4o-mini is cheap (~$0.15/1M input). GPT-4o is expensive (~$2.50/1M input). o1 is very expensive (~$15/1M).

Alternatives

  • Anthropic (Claude) — Different model, similar API, sometimes better at coding.
  • Google (Gemini) — Different model, integrated with Google Cloud.
  • Ollama (local) — Free, private, lower quality.

Failure modes

  • Cost.
  • Rate limits.
  • Data privacy.
  • API changes.
  • Vendor lock-in.

, , ,