Step 3.7 Flash Open vs INMercury 2 Paid
Step 3.7 Flash vs Mercury 2 compared — price per token, context window, multimodality, openness and which to choose. Can the open-source model replace the paid one? Full 2026 breakdown.
Prices & specs refreshed from live data · olud.ai
Open-model prices = cheapest provider via OpenRouter; official maker rates may be higher.
$1.15 /M outputNo per-token fees if you self-host
$0.75 /M outputManaged API (no infra to run)
Step 3.7 Flash vs Mercury 2 specs
| Spec | Step 3.7 Flash | Mercury 2 | Winner |
|---|---|---|---|
| Maker | Stepfun | Inception | – |
| Type | Open-weight | Proprietary | |
| Context window | 262K tokens | 128K tokens | |
| Input price | $0.2/M · free self-host | $0.25/M | |
| Output price | $1.15/M · free self-host | $0.75/M | INMercury 2 |
| Vision / multimodal | Yes | No | |
| Tool / function calling | Yes | Yes | = Tie |
| Self-hostable | Yes | No (API only) | |
| License | Open weights | Proprietary |
Price gap & when to choose each
Mercury 2 is ~1.5× cheaper than Step 3.7 Flash on output tokens ($0.75 vs $1.15 per M tokens).
- You want to self-host or run on your cloud
- You need the longer 262K context window
- You prioritize data privacy & control
- You are building open or reproducible AI
- You want frontier performance through a managed API
- You want the lower output price
- You value reliability & ecosystem
- You don't want to manage infrastructure
Feature comparison
| Capability | Step 3.7 Flash | Mercury 2 |
|---|---|---|
| Open weights (downloadable) | ✓ | ✗ |
| Self-hostable | ✓ | ✗ |
| Runs fully offline | ✓ | ✗ |
| Vision / multimodal | ✓ | ✗ |
| Tool / function calling | ✓ | ✓ |
| 1M+ context window | ✗ | ✗ |
Benchmarks: Step 3.7 Flash vs Mercury 2
Independent benchmark scores measured by Artificial Analysis. Higher is better (except latency).
Benchmark data by Artificial Analysis.
How Step 3.7 Flash and Mercury 2 score
| Criterion | Step 3.7 Flash | Mercury 2 |
|---|---|---|
| Cost-efficiency | 4.5 | 5.0 |
| Context window | 4.0 | 3.5 |
| Openness | 5.0 | 1.5 |
| Self-hosting | 5.0 | 1.0 |
| Multimodality | 5.0 | 3.5 |
Scores come from live data — output price (cost), context length, open vs closed weights (openness & self-hosting) and vision/tool support (multimodality). Raw task quality isn't scored here; it depends on your benchmark — see the verdict.
What each model is
Step 3.7 Flash Open
Step 3.7 Flash is StepFun's latest high-efficiency multimodal Mixture-of-Experts model. It pairs a 196B-parameter language backbone with a vision encoder for native image and video understanding, activating roughly 11B parameters...
Mercury 2 Paid
Mercury 2 is an extremely fast reasoning LLM, and the first reasoning diffusion LLM (dLLM). Instead of generating tokens sequentially, Mercury 2 produces and refines multiple tokens in parallel, achieving...
Other models in these families
These variants are tracked but not compared here — one page per family keeps the comparison readable.
Frequently asked questions
Is Step 3.7 Flash as good as Mercury 2?
Step 3.7 Flash is open-weight and competitive on many tasks, but Mercury 2 may still lead on the hardest reasoning and agentic work. The gap keeps narrowing — benchmark both on your actual use case before deciding.
Can I run Step 3.7 Flash locally?
Yes. Step 3.7 Flash has open weights, so you can self-host it on your own GPUs or run it via a low-cost API. Mercury 2 is API-only and cannot be self-hosted.
Step 3.7 Flash vs Mercury 2 — which should I pick in 2026?
Choose Step 3.7 Flash if you want to self-host, keep your data private and skip per-token fees — it's open-weight and runs on your own hardware. Choose Mercury 2 if you want frontier capability through a managed API with zero infrastructure to run.
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