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StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)
- skysniper 6mo agoI ran 300+ benchmarks across 15 models in OpenClaw and published two separate leaderboards: performance and cost-effectiveness. The two boards look nothing alike. Top 3 performance: Claude Opus 4.6, GPT-5.4, Claude Sonnet 4.6. Top 3 cost-effectiveness: StepFun 3.5 Flash, Grok 4.1 Fast, MiniMax M2.7. The most dramatic split: Claude Opus 4.6 is #1 on performance but #14 on cost-effectiveness. StepFun 3.5 Flash is #1 cost-effectiveness, #5 performance. Other surprises: GLM-5 Turbo, Xiaomi MiMo v2 Pro, and MiniMax M2.7 all outrank Gemini 3.1 Pro on performance. Rankings use relative ordering only (not raw scores) fed into a grouped Plackett-Luce model with bootstrap CIs. Same principle as Chatbot Arena — absolute scores are noisy, but "A beat B" is reliable. Full methodology: https://app.uniclaw.ai/arena/leaderboard/methodology?via=hn https://app.uniclaw.ai/arena/leaderboard/methodology?via=hn I built this as part of OpenClaw Arena — submit any task, pick 2-5 models, a judge agent evaluates in a fresh VM. Public benchmarks are free.
- refulgentis 6mo agoPlease don’t use AI to write comments, it cuts against HN guidelines.
- skysniper 6mo agosorry didn't know that. Here is my hand writing tldr: gemini is very unreliable at using skills, often just read skills and decide to do nothing. stepfun leads cost-effectiveness leaderboard. ranking really depends on tasks, better try your own task.
- refulgentis 6mo agoIt’s too late once it’s happened. I was curious, then when I saw the site looked vibecoded and you’re commenting with AI, I decided to stop trying to reason through the discrepancies between what was claimed and what’s on the site (ex. 300 battles vs. only a handful in site data).
- skysniper 6mo agoall 300+ battle data are available at https://app.uniclaw.ai/arena/battles https://app.uniclaw.ai/arena/battles, every single battle is shown with raw conversional history, produced files, judge's verdict and final scores
- refulgentis 6mo agoThanks! Is the judge an LLM? There's lot of references to "just like LMArena", but LMArena is human evaluated?
- skysniper 6mo ago> Is the judge an LLM? Yes, judge is one of opus 4.6, gpt 5.4, gemini 3.1 pro (submitter can choose). Self judge (judge model is also one of the participants) is excluded when computing ranking. > There's lot of references to "just like LMArena", but LMArena is human evaluated? Yeah LMArena is human evaluated, but here i found it not practical to gather enough human evaluation data because the effort it take to compare the result is much higher: - for code, judge needs to read through it to check code quality, and actually run it to see the output - when producing a webpage or a document, judge needs to check the content and layout visually - when anything goes wrong, judge needs to read the execution log to see whether partial credit shall be granted if you look at the cost details of each battle (available at the bottom of battle detail page), judge typically cost more than any participant model. if we evaluate with human, i would say each evaluation can easily take ~5-10 min
- refulgentis 6mo agoFair enough, yeah, agent evals are hard especially across N models :/ Thanks for replying btw, didn't mean any disrespect, good on you for not getting aggro about feedback
- skysniper 6mo agoI appreciate honest feedback, best way to learn :)
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- johndough 6mo agoCould you add a column for time or number of tokens? Some models take forever because of their excessive reasoning chains.
- skysniper 6mo agoboth are shown in battle detail page already. Time is shown in Scores table. Number of tokens are shown in Cost details at the bottom of the Scores. (I thought most people just want to see cost in USD so I put token details at the bottom)
- hadlock 6mo agosome kind of top-level metric like avg tokens/task would be useful. e.g. yes stepfun is 5% the price of sonnet, but does it use 1x, 10x or 1000x more tokens to accomplish similar tasks/median per task. for example I am willing to eat a 20% quality dive from sonnet if the token use is < 10% more than sonnet. if token use is 1000x then that's something I want to know.
- skysniper 6mo agoadded https://app.uniclaw.ai/arena/model-stats https://app.uniclaw.ai/arena/model-stats also added per battle stats in battle detail page
- johndough 6mo agoI would have liked aggregated results instead. Expanding 300 tables is a bit tiresome. But I guess that is easy with AI now. Here is a scatter plot of quality vs duration https://i.imgur.com/wFVSpS5.png https://i.imgur.com/wFVSpS5.png and quality vs cost https://i.imgur.com/fqM4edw.png https://i.imgur.com/fqM4edw.png But I just noticed that my plot is meaningless because it conflates model quality with provider uptime. Claude Haiku has a higher average quality than Claude Opus, which does not make sense. The explanation is that network errors were credited with a quality score of 0, and there were _a lot_ of network errors.
- 6mo ago
- citizenpaul 6mo ago>Other surprises: GLM-5 Turbo, Xiaomi MiMo v2 Pro, and MiniMax M2.7 all outrank Gemini 3.1 Pro on performance This has also been my subjective experience But has also been objective in terms of cost.
- vessenes 6mo agoCheapest just isn't a very useful metric. Can I suggest a Pareto-curve type representation? Cost / request vs ELO would be useful and you have all the data.
- skysniper 6mo agoTBH that was my initial thought too, but I found some problem using this approach: Essentially I'm using the relative rank in each battle to fit a latent strength for each model, and then use a nonlinear function to map the latent strength to Elo just for human readability. The map function is actually arbitrary as long as it's a monotonically increasing function so it preserves the rank. The only reliable result (that is invariant to the choice of the function) is the relative rank of models. That being said, if I use score/cost as metrics, the rank completely depends on the function I choose, like I can choose a more super-linear function to make high performance model rank higher in score/cost board, or use a more sub-linear function to make low performance model rank higher. That's why I eventually tried another (the current) approach: let judge give relative rank of models just by looking at cost-effectiveness (consider both performance and cost), and compute the cost-effectiveness leaderboard directly, so the score mapping function does not affect the leaderboard at all.
- hadlock 6mo agoAccording to openrouter.ai it looks like StepFun 3.5 Flash is the most popular model at 3.5T tokens, vs GLM 5 Turbo at 2.5T tokens. Claude Sonnet is in 5th place with 1.05T tokens. Which isn't super suprising as StepFun is ~about 5% the price of Sonnet. https://openrouter.ai/apps?url=https%3A%2F%2Fopenclaw.ai%2F https://openrouter.ai/apps?url=https%3A%2F%2Fopenclaw.ai%2F
- skysniper 6mo agothe real surprising part to me is that, despite being the cheapest model on board, stepfun is often able to score high at pure performance. Other models at the same price range (e.g. kimi) fails to do that.
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- NitpickLawyer 6mo ago> the most popular model It was free for a long time. That usually skews the statistics. It was the same with grok-code-fast1.
- gunalx 6mo agoGlm also has their subscription witch I would assume heavy users to use.
- arjie 6mo agoI used to use these various models for my claw-like and what they had a habit of doing is taking way more agent rounds and way more tokens to produce something that Sonnet would produce from far less. My total cost ended up being the same to do useful things.
- smallerize 6mo agoIt looks like Unsloth had trouble generating their dynamic quantized versions of this model, deleted the broken files, then never published an update.
- WhitneyLand 6mo agoStepFun is an interesting model. If you haven’t heard of it yet there’s some good discussion here: https://news.ycombinator.com/item?id=47069179 https://news.ycombinator.com/item?id=47069179
- tarruda 6mo agoSince that discussion, they released the base model and a midtrain checkpoint: - https://huggingface.co/stepfun-ai/Step-3.5-Flash-Base https://huggingface.co/stepfun-ai/Step-3.5-Flash-Base - https://huggingface.co/stepfun-ai/Step-3.5-Flash-Base-Midtrain https://huggingface.co/stepfun-ai/Step-3.5-Flash-Base-Midtra... I'm not aware of other AI labs that released base checkpoint for models in this size class. Qwen released some base models for 3.5, but the biggest one is the 35B checkpoint. They also released the entire training pipeline: - https://huggingface.co/datasets/stepfun-ai/Step-3.5-Flash-SFT https://huggingface.co/datasets/stepfun-ai/Step-3.5-Flash-SF... - https://github.com/stepfun-ai/SteptronOss https://github.com/stepfun-ai/SteptronOss
- lostmsu 6mo agoTuned Qwen 3.5 27B beats Step 3.5 on almost all benchmarks, so the point about the size class is moot.
- tempaccount420 6mo agoBenchmarks are not interesting in deciding the "size class". Bigger size means more knowledge. Also, the Qwen 3.5 27B is a dense 27B active parameter model. StepFun 3.5 Flash has 11B active parameters.
- lostmsu 6mo ago> Bigger size means more knowledge. Qwen 3.5 27B beats StepFun 3.5 Flash on GPQA Diamond too, so probably no.
- tarruda 6mo ago
- skysniper 6mo agoanother thing from the bench I didn't expect: gemini 3.1 pro is very unreliable at using skills. sometimes it just reads the skill and decide to do nothing, while opus/sonnet 4.6 and gpt 5.4 never have this issue.
- zhangchen 6mo ago[flagged]
- throwa356262 6mo agoGemini 2.5 pro was the best Gemini, it has gone downhill since
- hypercube33 6mo agoI used sonnet and opus 4.6 for a month and it flat out ignored skills and rules and when asked it said it knew better or was lazy.
- dmazin 6mo agowhy do half the comments here read like ai trying to boost some sort of scam?
- deleted 6mo ago[deleted]
- Capricorn2481 6mo agoBecause there's absolutely nothing stopping that from happening. There are bots on Reddit, there are of course bots on here, a VPN friendly site where you don't even need an email. But a lot of people don't want to admit it.
- grimm8080 6mo agoYet when I tried it it did absymal compared to Gemini 2.5 Flash
- skysniper 6mo agowhat kind of tasks did you try?
- sunaookami 6mo agoTried the free version on OpenRouter with pi.dev and it's competent at tool calling and creative writing is "good enough" for me (more "natural Claude-level" and not robotic GPT-slop level) but it makes some grave mistakes (had some Hanzi in the output once and typos in words) so it may be good with "simple" agentic workflows but it's definitely not made for programming nor made for long writing.
- skysniper 6mo agoit's actually pretty good at openclaw type of tasks for non technical users: lots of tool calls, some simple programing
- sunaookami 6mo agoYeah this kind of stuff. I have no experience with OpenClaw though.
- admiralrohan 6mo agoWhat kind of creative writing are you doing? Fiction or non-fiction like blog posts?
- sunaookami 6mo agoFiction. One of my "benchmarks" is giving the model a bunch of (self-made) text and having it simulate a 4chan thread about it. This tests tool use (calling the APIs), some skills, censorship and general creativity. Some models refuse every new turn after reading real 4chan threads ;) Claude is especially good at this surprisingly while GPT fails spectacularly and Gemini is just lazy (and barely usable since it's constantly overloaded). Qwen (coder-model from Qwen CLI, so Qween 3.5) is also very good but sadly not usable in Pi (they detect and block calls outside their CLI).
- admiralrohan 6mo agoInteresting. Are you running something like Autoresearch loop for writing fiction? How will the agent determine whether the output is good as this is subjective.
- mgw 6mo agoMissing from the comparison is MiMo V2 Flash (not Pro), which I think could put up a good fight against Step 3.5 Flash. Pricing is essentially the same: MiMo V2 Flash: $0.09/M input, $0.29/M output Step 3.5 Flash: $0.10/M input, $0.30/M output MiMo has 41 vs 38 for Step on the Artificial Analysis Intelligence Index, but it's 49 vs 52 for Step on their Agentic Index.
- skysniper 6mo agoI will try and add it. But I doubt it works well because Mimo V2 Pro is beaten by stepfun even at performance leaderboard (price is not a factor in this leaderboard), so I expect MiMo V2 Flash to perform even worse.
- ygouzerh 6mo agoMimo V2 Pro seems quite used by people as per OpenRouter's stats (second after Stepfun), it could be interesting to see indeed the difference! https://openrouter.ai/apps?url=https%3A%2F%2Fopenclaw.ai%2F https://openrouter.ai/apps?url=https%3A%2F%2Fopenclaw.ai%2F
- nl 6mo agoMimi Flash matched Mimo Pro on https://sql-benchmark.nicklothian.com/?#all-data https://sql-benchmark.nicklothian.com/?#all-data at double the speed and for $0.003 instead of $0.07
- throwa356262 6mo agoInteresting, I found the pro version to be very capable. If stepfun is even better, then Chinese models are getting really good.
- grigio 6mo agoi like StepFun 3.5 Flash, a good tradeoff
- yieldcrv 6mo agopeople aren't just using Claude models any more? that's nice to see
- skysniper 6mo agowell, I still want to use it but the first day i tried openclaw + opus, it costs me ~$500...
- aplomb1026 6mo ago[dead]
- james2doyle 6mo agoNone of the Qwen 3.5 models seem present? I’ve heard people are pretty happy with the smaller 3.5 versions. I would be curious to see those too. I would also be interested to see "KAT-Coder-Pro-V2" as they brag about their benchmarks in these bots as well
- Aerroon 6mo agoIf they use OpenRouter pricing then the Qwen3.5 models are going to be poor value. The Qwen3.5 27B model on OR is $1.56/million tokens out (it used to be $2.4/mil). Meanwhile Minimax M2.7 (a much larger model) is $1.2/mil out. The smaller and medium tier Qwen3.5 models are only really cost effective if you run them yourself.
- p1necone 6mo agoIs Minimax M2.7 better than Qwen3.5 27B, or is it just bigger?
- kdasme 6mo agoMinimax M2.7 is similar to sonnet in my tests. This is the first non OAI/Anthropic model I use for coding. It does require more steering, though.
- wg0 6mo agoMore steering than Sonnet? What is your experience?
- wilj 6mo agoI'm about 2 days into transitioning, using MiMo V2 Pro in place of Opus and MiniMax M2.7 in place of Sonnet. I'm finding that the extra "hand holding" that MiMo and MiniMax need isn't really "extra." The Anthropic models happily agree to a plan and then do something else entirely way too often. With MiMo and MiniMax I'm just spreading the attention throughout the day instead of big spikes of frustration figuring out where Claude went off the rails.
- ipython 6mo agoI was excited to read through this to find out how these tasks are evaluated at scale. Lots of scary looking formulas with sigmas and other Greek letters. Then I clicked on one task to see what it looks like “on the ground”: https://app.uniclaw.ai/arena/DDquysCGBsHa https://app.uniclaw.ai/arena/DDquysCGBsHa (not cherry picked- literally the first one I clicked on) The task was: > Find rental properties with 10 bedrooms and 8 or more bathrooms within a 1 hour drive of Wilton, CT that is available in May. Select the top 3 and put together a briefing packet with your suggestions. Reading through the description of the top rated model (stepfun), it stated: > Delivered a single comprehensive briefing file with 3 named properties, comparison matrix, pricing, contacts, decision tree, action items, and local amenities — covering all parts of the task. Oh cool! Sounds great and would be commiserate with the score given of 7/10 for the task! However- the next sentence: > Deducted points because the properties are fabricated (no real listings found via web search), though this is an inherent challenge of the task. So…… in other words, it made a bunch of shit up (at least plausible shit! So give back a few points!) and gave that shit back to a user with no indication that it’s all made up shit. Ok, closed that tab.
- skysniper 6mo agoI know, that was indeed a bad judge move. I've manually checked tens of tasks so far, and that one is one of the worst... I would say check a few more, judge has some noise but in general did a good job IMO
- ipython 6mo agoWhy not re run your analysis with improved judging criteria?
- chrisweekly 6mo ago"commiserate" - did you mean "commensurate"?
- ipython 6mo agoSorry, yes. I was typing quickly
- jghiglia 6mo ago[flagged]
- Caum 6mo ago[flagged]
- azmenak 6mo agoThis model is free to use, and has been for quite some time on OpenRouter. $0 is pretty hard to beat in terms of cost effectiveness.
- skysniper 6mo agoyeah but i'm not using the free version for benchmark...
- mtrifonov 6mo ago[dead]
- clausewitz 6mo agoI'm not seeing Deepseek mentioned very often, which I've been using for Openclaw, very cheaply I might add, with great success. I think I loaded $10 to my account 2 months ago and I still havent needed to top up.
- wg0 6mo agoWhich deepseek exactly and what do you use it for? Just curious.
- hyperlambda 6mo ago[flagged]
- philbitt 6mo ago[dead]