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.
| Claude Opus 4.8 anthropic/claude-opus-4.8 | GPT-5.5 Pro openai/gpt-5.5-pro | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Family | Claude 4 | GPT-5 |
| Modality | text | text |
| Context window | 1,000,000 tok | 1,000,000 tok |
| Max output | 128,000 tok | 16,384 tok |
| Released | 2026-05-28 | 2026-05-22 |
| Input price | $5.00 /1M | $30.00 /1M |
| Output price | $25.00 /1M | $180.00 /1M |
| Cache read | $0.500 /1M | — |
| Tools | yes | yes |
| Streaming | yes | yes |
| Vision | yes | yes |
| JSON mode | yes | yes |
| Reasoning | yes | yes |
| Prompt caching | yes | — |
Claude Opus 4.8 is Anthropic's most capable generally available model, with a step-change improvement in agentic coding over Claude Opus 4.7. It uses adaptive thinking to calibrate reasoning per task and supports a one million token context window at standard pricing.
GPT-5.5 pro uses OpenAI's Responses API with built-in tools, improved reasoning, and stateful context management.
# 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 Claude Opus 4.8
client.chat.completions.create(
model="anthropic/claude-opus-4.8",
messages=[{"role":"user","content":"hello"}],
)
# Try GPT-5.5 Pro — same client, same key
client.chat.completions.create(
model="openai/gpt-5.5-pro",
messages=[{"role":"user","content":"hello"}],
)