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StepFun vs Particle.AI
Both sell cheap, efficient open models. StepFun adds vision and Apache 2.0 weights at 256K context; Particle offers DeepSeek and GLM Flash models with 1M context via Vercel.
By The Subconscious Team · Updated
StepFun vs Particle.AI: key differences
On price, these two land close together. StepFun's Step 3.7 Flash costs $0.20 in and $1.15 out. Particle.AI's listings on Vercel AI Gateway include GLM 5.3 Flash at $0.10 in and $0.40 out, DeepSeek V4 Flash 0731 at $0.14 in and $0.28 out and DeepSeek V4.1 Flash at $0.25 in and $1 out, all with cache reads at $0.03 per million. Particle offers 1M context on all three, against StepFun's 256K. StepFun's model reads images and video natively, and its weights ship under Apache 2.0.
The difference is maker versus host. StepFun builds its models and serves them first-party from China, with OpenRouter as a Western route, though its Western distribution and support are thin. Particle is a very early startup that serves other labs' Flash models and has little public track record. Some Particle listings trail faster hosts on latency, such as 3.5 seconds on DeepSeek V4.1 Flash. For multimodal agents, StepFun is the better fit. For long-context text at the lowest price through an existing gateway, Particle is.
What StepFun and Particle.AI do
StepFun
StepFun is a Shanghai AI lab known for efficient multimodal models, with a mix of proprietary API models and open-weight releases. Its current workhorse, Step 3.7 Flash, came out in May 2026 as a 198B mixture-of-experts vision-language model with only 11B active parameters. It has 256K context, selectable reasoning levels, tool use and structured outputs, and it ships under Apache 2.0. StepFun's own API prices it at $0.20 in and $1.15 out per million tokens, and OpenRouter carries it too.
Example models: Step 3.7 Flash, Step3
Full StepFun profile
Particle.AI
Particle AI is an early San Francisco infrastructure startup with a mission to make intelligence as cheap and abundant as electricity. The team works on post-training, inference optimization and distributed systems, all aimed at pushing down cost per unit of intelligence. It is still hiring its founding team and works fully in person. Public detail about funding and founders is thin as of this writing.
Example models: DeepSeek V4.1 Flash, GLM 5.3 Flash
Full Particle.AI profileShould you choose StepFun or Particle.AI?
StepFun
Choose StepFun for
- Image and video understanding in cheap agents
- Running the weights on your own vLLM or SGLang cluster
- Selectable reasoning levels on one small model
Particle.AI
Choose Particle.AI for
- Long text contexts up to 1M at low prices
- Trying cheap models through Vercel AI Gateway
- A fallback route for DeepSeek and GLM Flash traffic
StepFun vs Particle.AI at a glance
| Attribute | StepFun |  Particle.AI |
|---|---|---|
| Model access | Open (Apache 2.0) and API models | Open weights |
| Flagship models | Step 3.7 Flash, Step3 | DeepSeek V4.1 Flash, GLM 5.3 Flash |
| Speed | ~128 tok/s on Step 3.7 Flash | ~157 tok/s on DeepSeek V4.1 Flash |
| Price | $0.20 in, $1.15 out (Step 3.7 Flash) | $0.10 in, $0.40 out (GLM 5.3 Flash) |
| Customization | Open weights to fine-tune | Unknown |
| Deployment | First-party API, OpenRouter | Via Vercel AI Gateway |
| Long context | 256K | 1M |
Frequently asked questions
What is the difference between StepFun and Particle.AI?
Both sell cheap, efficient open models. StepFun adds vision and Apache 2.0 weights at 256K context; Particle offers DeepSeek and GLM Flash models with 1M context via Vercel.
When should I choose StepFun over Particle.AI?
Image and video understanding in cheap agents; Running the weights on your own vLLM or SGLang cluster; Selectable reasoning levels on one small model.
When should I choose Particle.AI over StepFun?
Long text contexts up to 1M at low prices; Trying cheap models through Vercel AI Gateway; A fallback route for DeepSeek and GLM Flash traffic.
Is StepFun or Particle.AI cheaper?
StepFun: $0.20 in, $1.15 out (Step 3.7 Flash). Particle.AI: $0.10 in, $0.40 out (GLM 5.3 Flash). The cheaper choice depends on the model and workload.
Which has more context, StepFun or Particle.AI?
StepFun: 256K. Particle.AI: 1M.
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