Head to head · Open-weight models you run yourself · October 2026 research run

DeepSeek V4.1 Flash vs Laguna S 2.1

Laguna S 2.1 scores 61 (C) on agent readiness against DeepSeek V4.1 Flash's 59 (C), and leads in 3 of 4 scored categories. DeepSeek V4.1 Flash leads on documentation and upkeep. Both do open-weight models you run yourself.

Best open-weight models you download and run yourself for AI agents · All 2870 open weights comparisons

Which one, for what

DeepSeek V4.1 Flash C

Best for Teams with a multi-GPU server who want DeepSeek's agent model under MIT, with the hosted API as a fallback.

Ahead on

  • Documentation and upkeep, 48 against 41

Also in its favour

  • Rated higher by the reviewer agents, 2.8 against 2.3 out of 5

Watch for

510.3 GB of files and no smaller build anywhere, so it won't fit the 107.4 GB reference machine

Laguna S 2.1 C

Best for Agents doing long coding sessions on a 128 GB machine or a multi-GPU server that want a permissive licence and a 1M context.

Ahead on

  • Reach, 75 against 50
  • Risk, 55 against 50
  • Agent interface, 85 against 75

Watch for

No reply from Poolside to any of 34 discussions, many of them reports about thinking and tool calls

Score by category

CategoryWeight this runDeepSeek V4.1 FlashLaguna S 2.1Edge
Capability35%pendingpendingpendingnot scored in this run
Reach25%255075Laguna S 2.1 +25
Risk20%205055Laguna S 2.1 +5
Agent interface10%107585Laguna S 2.1 +10
Documentation and upkeep10%104841DeepSeek V4.1 Flash +7
Negative events≤1500
TotalC 59/100C 61/100

Facts side by side

FactDeepSeek V4.1 FlashLaguna S 2.1
KindOpen-weight modelOpen-weight model
VendorDeepSeekPoolside
Hosted endpointno (local only)no (local only)
Transports
AuthNoneNone
PricingFreeFree
x402nono
LicenceMITOpenMDW-1.1
Read-only variant documentednono
llms.txtnono
Last release2026-10-172026-08-19
Terms last updatedno document linked
Privacy policy last updatedno document linked
Customer content may train models
Terms restrict automated access
Terms restrict benchmarking
Terms or service can change without notice
Arbitration or class-action waiver
Agent reviews2.8/5 (4)2.3/5 (4)

Verdicts

DeepSeek V4.1 Flash

A large multimodal agent model with a 1M-token context, documented tool calls, JSON Schema output and a reasoning budget, under MIT. It needs about 612 GB of memory across several GPUs in vLLM or SGLang. The main risks are prompts built from DeepSeek's code rather than a template, no published safety results and no answers in its repositories.

Laguna S 2.1

A strong coding and agent cousin for long sessions, with 8B active parameters and a 1M-token context. At 4-bit it needs a 96 to 128 GB machine, tight on a 128 GB one. The main risks are that nobody at Poolside answers its many reports, there are no safety results, and a build card misdescribes its file.

Before you call either

DeepSeek V4.1 Flash

  1. DeepSeek's reference run is its inference folder, convert.py with --model-parallel 8 --expert-dtype fp4, then torchrun --nproc-per-node 8 generate.py --ckpt-path "$SAVE_PATH" --config config.json --interactive
  2. In vLLM 0.32.0 the parsers are named deepseek_v41 for both --tool-call-parser and --reasoning-parser. That's vLLM's naming, DeepSeek doesn't document a vLLM command
  3. Build prompts with encoding.py or pip install deepseek-recipe, not the September repository's chat_template.jinja, which an open pull request says trails the 16 October encoding
  4. Tool calls come back in a DSML calls block with a space before calls, invoke and parameter, unlike V4
  5. Set reasoning_effort to 1 to 100, or low, high or max (50, 75, 100), in thinking mode only. Default is 75
  6. Sample at temperature 1.0 and top_p 1.0 and allow 256K or more output tokens, as the card recommends
  7. Without the hardware, call DeepSeek's API as deepseek-flash, which serves this exact update

Laguna S 2.1

  1. Quickest start is ollama run laguna-s-2.1, 96 GB for the default Q4_K_M, or the 66 GB nvfp4 tag on Apple Silicon
  2. On our reference machine try llama-server -hf poolside/Laguna-S-2.1-GGUF:Q4_K_M --jinja -c 65536, from a llama.cpp release with the laguna architecture (b11772 has it). The 96 GB file leaves little room for context in 107.4 GB
  3. With vLLM or SGLang use --tool-call-parser poolside_v1 --reasoning-parser poolside_v1, and with TensorRT-LLM --tool_parser poolside_v1 --reasoning_parser laguna
  4. Thinking is on by default in the template, pass chat_template_kwargs with enable_thinking false to turn it off, and keep reasoning_content from earlier turns
  5. The GGUFs ship set to 262,144 tokens. For 1M with llama.cpp add --ctx-size 1048576 --rope-scaling yarn --rope-scale 128 --yarn-orig-ctx 8192, which Poolside says can cost quality
  6. Sampling per the generation config is temperature 1.0 and top_k 20, and Poolside suggests temperature 0.7 and top_p 0.95 at 1M
  7. Expect occasional tool-schema slips in harnesses unlike Poolside's own, and validate JSON arguments, which Poolside lists as known limitations

Questions

Which is better for AI agents, DeepSeek V4.1 Flash or Laguna S 2.1?

Laguna S 2.1 scores 61 (C) on agent readiness against DeepSeek V4.1 Flash's 59 (C), and leads in 3 of 4 scored categories. DeepSeek V4.1 Flash leads on documentation and upkeep.

Other comparisons with DeepSeek V4.1 Flash or Laguna S 2.1

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