Claude is Anthropic's frontier family — the default choice for reasoning, coding and agentic workflows. Kunavo serves the whole family, from Haiku to the new Claude 5 generation (Fable 5, Opus 5, Sonnet 5), through both an OpenAI-compatible API and the native Anthropic Messages API, at 30% under Anthropic's list price depending on the model, on one Stripe-billed balance. This is the hub for everything Claude on Kunavo.
The product page, Claude API on Kunavo, lists the price of every Claude model next to Anthropic's list price. This guide covers the setup.
What you can do with the Claude API
- Reasoning & analysis — long-context document analysis, multi-step problem solving.
- Coding — generation, refactoring and review; Sonnet and Opus are strong agentic coders.
- Vision — image understanding alongside text.
- Tool use — function calling for agents and structured output.
- Prompt caching — cache large stable context and pay 10% of the input rate on cache hits, 2.5% on Claude Fable 5.1, 5% on Claude Opus 5.5.
Get a key and make your first call
Create a key at /app/keys, then keep the OpenAI SDK and point base_url at Kunavo. Step-by-step (and the native Messages API form) is in how to get a Claude API key.
import os
from openai import OpenAI
client = OpenAI(
api_key=os.environ["KUNAVO_API_KEY"],
base_url="https://api.kunavo.com/v1",
)
resp = client.chat.completions.create(
model="claude-sonnet-5",
messages=[{"role": "user", "content": "Explain the CAP theorem to a backend engineer."}],
)
print(resp.choices[0].message.content)Prefer Anthropic's native shape, with cache_control and extended thinking? The same key works against the Messages API (/v1/messages).
Claude models, and when to use each
Rates are per 1M tokens in USD as billed on Kunavo, with Anthropic's published list price alongside. Worked cost examples and the prompt-caching math are in the Anthropic API pricing guide.
| Model | Kunavo in / out | Anthropic list | Off list | Use it for |
|---|---|---|---|---|
claude-haiku-4-5 | $0.70 / $3.50 | $1.00 / $5.00 | ~30% | High-volume classification, support, simple extraction |
claude-sonnet-4-6 | $2.10 / $10.50 | $3.00 / $15.00 | ~30% | Previous-generation Sonnet for reasoning, RAG and coding |
claude-sonnet-5 | $1.40 / $7.00 | $2.00 / $10.00 | ~30% | Near-Opus coding and agentic quality at Sonnet cost |
claude-opus-4-7 | $3.50 / $17.50 | $5.00 / $25.00 | ~30% | Heavy reasoning |
claude-opus-5 | $3.50 / $17.50 | $5.00 / $25.00 | ~30% | Hard reasoning on a budget — same rate as Opus 4.7, half of Fable 5's list price |
claude-fable-5 | $7.00 / $35.00 | $10.00 / $50.00 | ~30% | Frontier reasoning, long-horizon agents, 1M context |
Pricing
Claude on Kunavo runs 30% under Anthropic's list: the Claude 4.x generation is 30% off (Sonnet 4.6 at $2.10/$10.50 per 1M vs $3.00/$15.00), Fable 5 is 30% off at $7.00/$35.00, and Opus 5 is 30% off at $3.50/$17.50 vs $5.00/$25.00. Sonnet 5 is 30% off at $1.40/$7.00 vs $2.00/$10.00. Full per-model rates, worked cost examples and the prompt-caching math are in the Claude API pricing guide.
Go deeper
- Claude API key & setup
- Claude API pricing 2026
- Calling Claude with the OpenAI SDK
- Anthropic prompt caching deep dive
- Messages API reference
Frequently asked questions
How do I get a Claude API key?
Create a Kunavo account, generate a key at /app/keys, and use it with base_url=https://api.kunavo.com/v1. See the full guide.
How much does the Claude API cost?
On Kunavo, Claude runs 30% under Anthropic's list price: Haiku 4.5 $0.70/$3.50, Sonnet 4.6 $2.10/$10.50, Opus 4.7 $3.50/$17.50 and the new Opus 5 at the same $3.50/$17.50 (30% off list), and Fable 5 $7.00/$35.00 per 1M tokens (30% off list). Sonnet 5 is $1.40/$7.00 (30% off list). Prompt caching bills cached input at 10% of the input rate.
Can I use the Anthropic SDK or Messages API?
Yes — both the OpenAI-compatible endpoint and the native Messages API (/v1/messages) work on the same key.
Which Claude model should I use?
claude-sonnet-5 is the newest Sonnet — near-Opus coding — and on Kunavo it costs less per token than claude-sonnet-4-6 ($1.40/$7.00 per 1M against $2.10/$10.50), which stays available for reasoning, RAG and coding setups already tuned on it. Use claude-haiku-4-5 for cheap high-volume tasks and claude-opus-5 for hard reasoning on a budget — near-flagship quality at $3.50/$17.50 per 1M, half of Claude Fable 5's list price and the same rate as the older claude-opus-4-7, so the upgrade costs nothing extra. Reserve claude-fable-5-1 — Anthropic's most capable model and the September 2026 successor to claude-fable-5 at the same official price — for frontier reasoning and long-horizon agents.