python stream = client.chat.completions.create( model="gpt-5", messages=[{"role": "user", "content": "Hello"}], stream=True ) for chunk in stream: print(chunk.choices[0].delta.content or "", end="", flush=True)

Step 6 — System Prompt

python messages=[ {"role": "system", "content": "You are a helpful coding assistant."}, {"role": "user", "content": "..."} ]

Step 7 — Function Calling

See [what is tool calling](https://vibecodingturkey.com/en/rehberler/what-is-tool-calling).

gpt-5: flagship, $15/$60 per M tokens - gpt-5-mini: cheap + fast, $0.30/$1.20 - gpt-5-nano: cheapest, $0.05/$0.20 - o3 series: reasoning-specialized

python embedding = client.embeddings.create( model="text-embedding-3-small", input="The text to embed" ).data[0].embedding

Free tier: 3 RPM. Tier 1 ($5 spent): 500 RPM. Tier 5 ($1000+): much higher.

How to Use OpenAI API 2026 — Guide

Q: Step 4 — First Request

python from openai import OpenAI client = OpenAI() response = client.chat.completions.create( model="gpt-5", messages=[{"role": "user", "content": "Hello"}] ) print(response.choices[0].message.content)

How to Use OpenAI API 2026

OpenAI API is the most widely-integrated AI API. This guide gets you from zero to production. Step 1 — Sign Up platform.openai.com → Sign Up. Email + phone verification. Step 2 — Add Credit Billing → add $5+. Card or invoice. Step 3 — API Key API Keys → Create. Save it securely. Step 4 — First Request python from openai import OpenAI client = OpenAI response = client.chat.completions.create model…

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