Kimi K3 vs Claude Fable 5 on DeepSWE: Cost and Coding

Key Takeaways

Kimi K3 matches Claude Fable 5 on quality, costs a third as much per solved task, and as an open model gives teams full control over their deployment.

Kimi K3 vs Claude Fable 5 is close on DeepSWE pass@1: Fable leads 69.9% to 68.5%, a 1.4 point gap.

Give the models more attempts and Kimi K3 pulls ahead. It wins pass@2 (82.0 vs 80.2) and pass@4 (89.4% vs 88.5%).

Kimi K3 is far cheaper: \$4.65 per rollout vs \$13.41, and 2.8x more solved tasks per dollar.

Claude Fable 5 is the more reliable model: it solves more tasks four-for-four (58 vs 45).

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In our Kimi K3 vs Claude Fable 5 comparison on DeepSWE, a benchmark that tests a model's software engineering capabilities across many task types and programming languages, the most interesting model this month is not the one at the top of the leaderboard. It is Kimi K3, the new open-weight model parked 1.4 points behind Claude Fable 5, at a third of the price.

Kimi K3 landed in DeepSWE on July 16, 2026, with 452 graded rollouts at max effort: 113 real, long-horizon feature requests from live open-source repos, four trials each, graded pass/fail by a hidden test suite. We analyzed all of them against Claude Fable 5 at its best setting (xhigh), An

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