Vast.ai
The cheapest GPU cloud marketplace for AI workloads
About Vast.ai
Vast.ai is a peer-to-peer GPU rental marketplace where individual hosts rent out their idle GPUs at deeply discounted rates. It's widely considered the cheapest way to access high-end NVIDIA GPUs (RTX 4090, A100, H100) for Stable Diffusion, ComfyUI, model training, and inference workloads. Renters bid on instances via on-demand or interruptible pricing, with full SSH/Docker access to ComfyUI and Automatic1111 templates.
Pros & Cons
Pros
- By far the cheapest way to rent RTX 4090s and A100s for ComfyUI and Stable Diffusion experimentation
- Wide selection of consumer GPUs (3090/4090) that other clouds rarely offer
- Per-second billing and instant boot make tinkering on a budget realistic
- Pre-built ComfyUI and Automatic1111 templates get you generating in under 5 minutes
- Independent storage volumes let you persist large model libraries cheaply
Cons
- Host quality varies — DLPerf scores and reviews matter when choosing an instance
- Interruptible instances can be preempted, which breaks long renders or training jobs
- Not SOC 2/HIPAA compliant — unsuitable for regulated client workloads
- Networking and disk I/O can be inconsistent on lower-tier hosts
Key Features
Marketplace Pricing
Hosts compete on price, driving GPU costs down to a fraction of major clouds.
On-Demand & Interruptible
Choose stable on-demand pricing or bid for interruptible instances at up to 50% extra savings.
Docker & Templates
One-click Docker templates for Stable Diffusion WebUI, ComfyUI, Jupyter, and PyTorch.
Wide GPU Selection
RTX 3090, 4090, A100, H100, H200 and more, often available globally.
Per-Second Billing
Granular billing with no minimum commitment.
DLPerf Benchmarks
Built-in performance scoring helps you compare hosts on real ML workloads, not just specs.
SSH & Jupyter Access
Full root access via SSH, web terminal, or Jupyter for custom ComfyUI nodes and extensions.
Storage Persistence
Rent storage independently to keep models and outputs across instance restarts.
Pricing
- Bid-based pricing
- Up to 50% cheaper than on-demand
- May be preempted by higher bids
- Best for fault-tolerant workloads
- Stable, non-preemptible instances
- Pay the host's listed rate
- Per-second billing
- Wide GPU choice
- Long-term reservations
- Discounted rates for committed usage
- Suited for production inference
Best For
ComfyUI Tinkering on a Budget
Hobbyists spin up an RTX 4090 for $0.20-0.35/hr to run heavy ComfyUI workflows without buying hardware.
LoRA & Dreambooth Training
Affordable A100/H100 access for fine-tuning Stable Diffusion checkpoints and LoRAs overnight.
Batch Image Generation
Render thousands of SDXL or Flux images in a few hours at marketplace pricing.
Model Benchmarking
Test inference performance across different GPU SKUs before committing to a production host.
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Featured In
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