Which AI Model Should You Use? GPT-5.5 vs Claude Sonnet (by Use Case)

Which AI model should you use?

Short answer: match the model to the job. Use a fast, fluent, low-cost model (GPT-5.5) for
translation, customer service, and business chat; use Claude Sonnet for code, long documents, and
hard reasoning; use a smaller GPT-class model for high-volume, low-cost tasks. With APIVAI all of
them are behind one OpenAI-compatible key, so you can switch per task by changing the model
field — no other code changes.

This page is a practical model-selection guide by use case.

Quick recommendation table

When to pick GPT-5.5

GPT-5.5 is the default for anything conversational and latency-sensitive: translation,
customer-service replies, live-stream interpreting, sales chat. It writes natural, idiomatic text
in many languages and is cheap enough through APIVAI to run at high volume.

from openai import OpenAI
client = OpenAI(api_key="YOUR_APIVAI_API_KEY", base_url="https://api.apivai.com/v1")
r = client.chat.completions.create(
    model="gpt-5.5",
    messages=[{"role": "user", "content": "Translate to Spanish: 欢迎光临，今天有特价"}],
)
print(r.choices[0].message.content)

When to pick Claude Sonnet

Pick Claude Sonnet when correctness and depth matter more than raw speed: writing/refactoring
code, working over long documents, or multi-step reasoning. Tools like Claude Code, Cursor, and
Cline pair naturally with it.

r = client.chat.completions.create(
    model="claude-sonnet-4-6",
    messages=[{"role": "user", "content": "Refactor this function and explain the change: ..."}],
)

When to pick a smaller model

For bulk jobs — classifying thousands of messages, simple FAQ replies, first-pass translation —
a smaller GPT-class model gives the lowest cost. Reserve the stronger models for the cases that
need them.

How to choose at runtime

Because every model is behind one OpenAI-compatible endpoint, route by task in your own code:

def model_for(task: str) -> str:
    return {
        "translate": "gpt-5.5",
        "support":   "gpt-5.5",
        "code":      "claude-sonnet-4-6",
        "bulk":      "gpt-4o-mini-class-name-from-/v1/models",
    }.get(task, "gpt-5.5")

Always confirm the exact names with GET /v1/models — availability varies by account and over
time.

FAQ

Can I switch models without changing my integration? Yes — they're all OpenAI-compatible
through APIVAI; change only the model string.

Which is cheapest? Smaller GPT-class models per token; but GPT-5.5 is already low-cost via
APIVAI and usually the better value for conversational work.

One key for all models? Yes — a single APIVAI key works across Claude and GPT models.

Get started

Grab an APIVAI key, list models with GET /v1/models, and route per task. Examples:
APIVAI examples repo.