Claude Opus 5.5 vs GPT OSS 120B
Price in rupees, context and benchmarks side by side; same key, a one-string switch.
Scores from LMArena and Epoch AI, as published; a blank cell means not measured there.
What a month costs on each
On a typical 75/25 input-output mix, GPT OSS 120B costs less (about 99% less than Claude Opus 5.5). Claude Opus 5.5 takes the longer prompt at 1M tokens. Try your own numbers in the cost calculator.
Call either one
curl https://rapidrouter.ai/api/v1/chat/completions \
-H "Authorization: Bearer $RAPIDROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model": "anthropic/claude-opus-5-5", "messages": [{"role": "user", "content": "Hello"}]}'
# the other one: change the model string
-d '{"model": "openai/gpt-oss-120b", ...}'Common questions
Which is cheaper, Claude Opus 5.5 or GPT OSS 120B?
GPT OSS 120B is cheaper on a typical mix of 75% input and 25% output tokens, by about 99%. Through Rapid Router both are billed at the provider list price per million tokens, in rupees.
Which has the larger context window?
Claude Opus 5.5, at 1M tokens. GPT OSS 120B offers 131K tokens.
Can I switch between Claude Opus 5.5 and GPT OSS 120B without changing code?
Yes. Both are callable at https://rapidrouter.ai/api/v1 with the same OpenAI-compatible request; only the model string changes (anthropic/claude-opus-5-5 or openai/gpt-oss-120b).
How do I pay for Claude Opus 5.5 or GPT OSS 120B in India?
Top up a Rapid Router balance with UPI or a card in rupees, get a GST invoice on every recharge, and both models debit that balance per request.