Pricing, context window, capabilities, and release date — pulled from each provider's public docs. Both are available via the same AIgateway OpenAI-compatible endpoint; flip the model string to switch.
Both models stream in parallel through your own AIgateway key. Tokens, latency, and cost update as they arrive.
| GPT-5.5 Pro openai/gpt-5.5-pro | Claude Sonnet 4.6 anthropic/claude-sonnet-4.6 | |
|---|---|---|
| Provider | OpenAI | Anthropic |
| Family | GPT-5 | Claude 4 |
| Modality | text | text |
| Context window | 1,000,000 tok | 200,000 tok |
| Max output | 16,384 tok | 128,000 tok |
| Released | 2026-04-24 | 2026-04-13 |
| Input price | $30.00 /1M | $3.00 /1M |
| Output price | $180.00 /1M | $15.00 /1M |
| Cache read | — | $0.300 /1M |
| Tools | yes | yes |
| Streaming | yes | yes |
| Vision | — | yes |
| JSON mode | yes | yes |
| Reasoning | yes | yes |
| Prompt caching | — | yes |
GPT-5.5 Pro uses OpenAI's Responses API with built-in tools, improved reasoning, and stateful context management.
Claude Sonnet 4.6 is Anthropic's latest balanced model offering strong coding, reasoning, and agentic capabilities with improved instruction following.
# pip install aigateway-py openai
# aigateway-py: sub-accounts, evals, replays, jobs, webhook verify.
# openai SDK: chat/embeddings/images/audio — drop-in compat per our SDK's own guidance.
from openai import OpenAI
client = OpenAI(
base_url="https://api.aigateway.sh/v1",
api_key="sk-aig-...",
)
# Try GPT-5.5 Pro
client.chat.completions.create(
model="openai/gpt-5.5-pro",
messages=[{"role":"user","content":"hello"}],
)
# Try Claude Sonnet 4.6 — same client, same key
client.chat.completions.create(
model="anthropic/claude-sonnet-4.6",
messages=[{"role":"user","content":"hello"}],
)