Kimi K3 vs Muse Spark 1.3 Contributor
Pricing, context window and real answers (September 2026)
Kimi K3 (Moonshot) and Muse Spark 1.3 Contributor (Meta), compared as you can actually call them on FastMetal. Both are served from the same OpenAI-compatible endpoint and API key; switching is a change to the model string.
Specs and pricing
 Kimi K3 |  Muse Spark 1.3 Contributor | |
|---|---|---|
| Provider | Moonshot | Meta |
| Input (per 1M tokens) | ¥504 | ¥17.59 |
| Output (per 1M tokens) | ¥2,520 | ¥35.18 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥1,764 | ¥35 |
| Context window | 1,048,576 tokens | 1,048,576 tokens |
| Release date | 7/16/2026 | 9/2/2026 |
| Input modalities | text, image | text, image, video, file, audio |
| Throughput (p50) | — | — |
| Arena · overall | #17 · ELO 1,485 | Unranked |
| Arena · Japanese | #2 · ELO 1,511 | Unranked |
| Arena · coding | #7 · ELO 1,538 | Unranked |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, Muse Spark 1.3 Contributor: ¥35.18 per 1M output tokens, 99% less than Kimi K3.
- If in doubt, try both on the same key. Switching is a change to the model string, and each is billed at its own rate.
Frequently asked questions
- Which is cheaper, Kimi K3 or Muse Spark 1.3 Contributor?
- Per 1M output tokens, Kimi K3 is ¥2,520 and Muse Spark 1.3 Contributor is ¥35.18 on FastMetal (yen, before tax), so Muse Spark 1.3 Contributor is cheaper.
- How do the context windows of Kimi K3 and Muse Spark 1.3 Contributor compare?
- Kimi K3 takes 1,048,576 tokens; Muse Spark 1.3 Contributor takes 1,048,576.
- Can I use Kimi K3 and Muse Spark 1.3 Contributor with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "kimi-k3" or "muse-spark-1.3-contributor" as the model. Each is billed at its own rate from the same prepaid balance.
Try both on one API key
Create an account and add credit to call Kimi K3 and Muse Spark 1.3 Contributor from the browser chat and the API. No monthly fee.
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