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Meituan
meituan/longcat-flash-chat
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LongCat Flash Chat

LongCat-Flash-Chat is a large-scale Mixture-of-Experts (MoE) model with 560B total parameters, of which 18.6B–31.3B (≈27B on average) are dynamically activated per input. It introduces a shortcut-connected MoE design to reduce communication overhead and achieve high throughput while maintaining training stability through advanced scaling strategies such as hyperparameter transfer, deterministic computation, and multi-stage optimization. This release, LongCat-Flash-Chat, is a non-thinking foundation model optimized for conversational and agentic tasks. It supports long context windows up to 128K tokens and shows competitive performance across reasoning, coding, instruction following, and domain benchmarks, with particular strengths in tool use and complex multi-step interactions.

9/9/2025
131,072 tokens
#125 Text (Coding)

Specifications

Modalities

Input
text
Output
text

Supported Parameters

max_tokens
response_format
structured_outputs
temperature
tool_choice
tools
top_p

Max Output Tokens

32,768

Data policy

Prompt retention
Unknown — we could not confirm
Training
Unknown — not declared

"Unknown" does not mean "safe". It means we could not confirm it.

Whether a provider trains on prompts is a declared value from our terms with them. Retention is determined from the upstream listing for every host this model can reach. Neither is guessed.

Frequently asked questions

Is LongCat Flash Chat available on FastMetal?
Not at the moment. GLM 5.3 Flash, from the same lab, is available on the FastMetal API today.
What is the context window of LongCat Flash Chat?
131,072 tokens, shared between the prompt and the response.
How does LongCat Flash Chat rank?
#167 on the public arena's Japanese board (ELO 1,310). Ranks move as the leaderboard is updated.

Leaderboard

Text
russianELO: 1,378
#175
CodingELO: 1,472
#125
MathELO: 1,415
#139
Creative WritingELO: 1,329
#206
Instruction FollowingELO: 1,387
#165
Hard PromptsELO: 1,426
#155
Multi-TurnELO: 1,391
#180
OverallELO: 1,401
#164
JapaneseELO: 1,310
#167
ChineseELO: 1,433
#156
KoreanELO: 1,325
#168
EnglishELO: 1,421
#152
frenchELO: 1,428
#138
germanELO: 1,378
#160
spanishELO: 1,409
#134

Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-10-22; category names mapped and ratings rounded by FastMetal.