Anthropic shipped Claude Opus 4.7 on April 16 at $5/$25 per 1M tokens with a 1M-token context. A week later OpenAI countered with GPT-5.5 at $5/$30 and 400K context. Both price-matched on input. Both want to be your default.
We ran them head-to-head on real workloads for two weeks. Here's when each wins.
| Opus 4.7 | GPT-5.5 | |
|---|---|---|
| Input / 1M tokens | $5.00 | $5.00 |
| Output / 1M tokens | $25.00 | $30.00 |
| Cached input (read) | $0.50 | $0.625 |
| Context window | 1,000,000 | 400,000 |
| Max output | 64K | 32K |
| Vision | ✓ | ✓ |
| Tool use / function calling | ✓ (best-in-class) | ✓ |
| Structured output (JSON mode) | ✓ | ✓ (strict schema) |
Opus is 17% cheaper on output — meaningful for any workload where responses are long. GPT-5.5 wins on strict structured output with the response_format JSON schema guarantee (Anthropic's tool-based JSON is flexible but not enforced at decode time).
NovAI routes both frontier APIs through one OpenAI-compatible endpoint. Same SDK, no vendor lock-in.
Get Free API Key →On TAU-bench (airline/retail multi-turn tool use): Opus 4.7 = 69%, GPT-5.5 = 61%. Opus is noticeably better at deciding when not to call a tool, which matters more than raw accuracy in agent loops.
On blind taste-tests of marketing copy, blog drafts, and fiction (n=300), GPT-5.5 won 54%, Opus 4.7 won 33%, tie 13%. GPT-5.5 sounds more like a person; Opus is precise but sometimes clinical.
Both support caching now, but Opus's cache is cheaper ($0.50 vs GPT's $0.625 per 1M cached-read tokens) and has a 1-hour TTL vs OpenAI's ~5 min. If you have a long system prompt you reuse, Opus saves more.
GPT-5.5's response_format: {type: "json_schema", strict: true} enforces the schema at the decoder level — you never get malformed JSON. Opus uses tool-based JSON which is reliable but can technically deviate. For mission-critical structured extraction → GPT-5.5.
Both handle images. GPT-5.5 edges ahead on chart/graph comprehension; Opus is better at dense document OCR + understanding combined.
Native tiers as of May 2026:
OpenAI Tier 1 : 500 RPM, 30K TPM (needs $5 deposit)
OpenAI Tier 5 : 10K RPM, 30M TPM (needs $1K+ spent)
Anthropic T1 : 50 RPM, 20K TPM (needs $5 deposit)
Anthropic T4 : 4K RPM, 400K TPM (needs $400+ spent)OpenAI is meaningfully more generous at the low-end — if you're just starting, you'll hit Anthropic rate limits first.
GPT-5.5 wins on raw ecosystem — LangChain, LlamaIndex, every wrapper defaults to OpenAI. Anthropic SDK is clean but the ecosystem is thinner. Switching via an OpenAI-compatible gateway removes this gap.
One OpenAI-compatible endpoint. Switch between Opus 4.7 and GPT-5.5 by changing one string. USDT/Alipay payment, no US address required.
Try NovAI Free →| Workload | Pick |
|---|---|
| Production coding assistant, IDE integration | Opus 4.7 |
| Long-document Q&A (>300K tokens) | Opus 4.7 |
| Multi-step tool-use agent | Opus 4.7 |
| Strict JSON extraction / structured data | GPT-5.5 |
| Marketing copy / SEO content / fiction | GPT-5.5 |
| Math / scientific reasoning | GPT-5.5 or DeepSeek V4 |
| Bulk classification, translation, summarization | DeepSeek V4 (neither frontier is worth it) |
If you have to pick one: Opus 4.7 for builders, GPT-5.5 for creators. Both are $5-tier frontier models for a reason. The real optimization is not picking one — it's routing per-task and using cheaper models (DeepSeek, GLM, Qwen) for the 80% of calls that don't need frontier quality.
Use TokenScope to see your actual token distribution before committing to either.