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Moonshot Launches Kimi K3.1 Pro, Closing In On Anthropic's Claude Opus 5.5
· Confirmed
In Short: Chinese AI startup Moonshot has launched Kimi K3.1 Pro, a model that is rapidly closing in on Anthropic's Claude Opus 5.5 in benchmark tests, according to The Decoder.
Kimi K3.1 Pro's performance on the Kimi Hallu Bench Hard test has improved significantly, with claim-level hallucinations falling from 23.4 percent with K3 to 8.3 percent with K3.1 Pro, according to Moonshot.
Anthropic's new flagship general-release model, Claude Opus 5.5, launched on September 22, 2026, and costs $4 per million input tokens and $20 per million output tokens, 20% less than Opus 5.
Moonshot's Kimi K3.1 Pro charges $2 per million input tokens and $10 per million output tokens, down from $3 and $15 for Kimi K3, which launched in July.
An August preprint introducing BenchBench-Protocol, a test of 149 modifications scientists made to published wet-lab protocols, found Kimi K3 and GPT-5.6 Sol statistically indistinguishable on single attempts; over 10 attempts, Kimi K3 scored higher.
On CursorBench 4.0, which recreates real coding sessions from the Cursor editor, Sonnet 5.5 scores 55.5 percent versus 34.1 percent, landing just two points below Opus 5.5 (57.8 percent).
On Terminal-Bench 4.0, Kimi K3.1 Pro scores 65.7%, Opus 5.5 scores 66.4%, and Astra scores 58.2%. On the Artificial Analysis Intelligence Index, Opus 5.5 scores 58 and Kimi K3.1 Pro scores 55.
Anthropic reported a $183 billion valuation in September following its latest funding round, a figure largely made possible by Claude’s popularity among enterprise customers.
Claude Haiku 5.5, launched by Anthropic, approaches the benchmark numbers achieved by the considerably more expensive Sonnet 5.5 and beats the recently released GPT-6 Luna across all benchmarks shared by Anthropic.
Developers can get started with Claude-Haiku-5.5 on the Claude Platform.
Kimi K3.1 Pro's performance and cost-effectiveness have been widely praised, with Claude Sonnet 5.5 running more than 30 percent faster and costing up to 30 percent less for most work compared to its predecessor.
What this adds
Chinese AI startup Moonshot has launched Kimi K3.1 Pro, a model that is rapidly closing in on Anthropic's Claude Opus 5.5 in benchmark tests, according to The Decoder. This aligns with prior reports that highlighted the model's improved performance and cost-effectiveness.
Background
Chinese AI startup Moonshot has launched Kimi K3.1 Pro, a model that is rapidly closing in on Anthropic's Claude Opus 5.5 in benchmark tests, according to The Decoder.
Chinese AI startup Moonshot has launched Kimi K3.1 Pro, a model that is rapidly closing in on Anthropic's Claude Opus 5.5 in benchmark tests, according to The Decoder.
What's confirmed
- Kimi K3.1 Pro's performance on the Kimi Hallu Bench Hard test has improved significantly, with claim-level hallucinations falling from 23.4 percent with K3 to 8.3 percent with K3.1 Pro, according to Moonshot.
- Anthropic's new flagship general-release model, Claude Opus 5.5, launched on September 22, 2026, and costs $4 per million input tokens and $20 per million output tokens, 20% less than Opus 5.
- Moonshot's Kimi K3.1 Pro charges $2 per million input tokens and $10 per million output tokens, down from $3 and $15 for Kimi K3, which launched in July.
- An August preprint introducing BenchBench-Protocol, a test of 149 modifications scientists made to published wet-lab protocols, found Kimi K3 and GPT-5.6 Sol statistically indistinguishable on single attempts; over 10 attempts, Kimi K3 scored higher.
- On CursorBench 4.0, which recreates real coding sessions from the Cursor editor, Sonnet 5.5 scores 55.5 percent versus 34.1 percent, landing just two points below Opus 5.5 (57.8 percent).
- On Terminal-Bench 4.0, Kimi K3.1 Pro scores 65.7%, Opus 5.5 scores 66.4%, and Astra scores 58.2%. On the Artificial Analysis Intelligence Index, Opus 5.5 scores 58 and Kimi K3.1 Pro scores 55.
- Anthropic reported a $183 billion valuation in September following its latest funding round, a figure largely made possible by Claude’s popularity among enterprise customers.
- Claude Haiku 5.5, launched by Anthropic, approaches the benchmark numbers achieved by the considerably more expensive Sonnet 5.5 and beats the recently released GPT-6 Luna across all benchmarks shared by Anthropic.
- Developers can get started with Claude-Haiku-5.5 on the Claude Platform.
- Kimi K3.1 Pro's performance and cost-effectiveness have been widely praised, with Claude Sonnet 5.5 running more than 30 percent faster and costing up to 30 percent less for most work compared to its predecessor.
What's still developing
- That is a stronger raw score than the comparison would predict for a “cheaper” model, and it is one reason Sonnet 5.5 shows up ahead of Opus 5.5 on BenchLM’s October 2026 coding leaderboard, where Sonnet 5.5 scored 84.2 against Opus 5.5’s 82.6, even though BenchLM still lists Opus 5.5 first in its overall coding ranking once other weighting factors are folded in.
- Muse Wonder ranks sixth on Artificial Analysis's benchmark at 77.44, behind GPT-5.6 Sol and Claude Opus 4.8, even as Meta charges up to $100 a month for its most capable tier.
- ⚠️ Note: the official model card benchmarks against Opus 4.6 Max, GPT-5.4 xHigh, and Gemini 3.1 Pro High — not Opus 4.7 or GPT-5.5.
- Anthropic today announced the new Claude Haiku 5.5 model, positioning it as the model of choice for high-volume, cost-sensitive tasks.
- Anthropic launched Claude Haiku 5.5 on Tuesday, completing its current model lineup with a small model built for high-volume, cost-sensitive workloads.
- Kimi K2.6, an open-weights model from Chinese startup Moonshot AI, won the challenge outright: 22 match points, 7-1-0.
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