RunPod and Vast.ai both let you rent GPU compute from a marketplace of hosts — no reserved capacity, pay by the hour. Both have RTX 4090s, A100s, H100s, and consumer-grade GPUs at prices well below AWS or Azure. But the two platforms have meaningfully different approaches to pricing, reliability, and user experience. Here's the detailed breakdown.
Pricing Comparison: Who's Actually Cheaper?
| GPU | RunPod On-Demand | RunPod Spot | Vast.ai (typical range) |
|---|---|---|---|
| RTX 3090 (24 GB) | $0.44/hr | $0.20–0.35/hr | $0.20–0.38/hr |
| RTX 4090 (24 GB) | $0.74/hr | $0.35–0.55/hr | $0.35–0.65/hr |
| A100 PCIe 80GB | $1.89/hr | $0.90–1.49/hr | $1.10–1.80/hr |
| A100 SXM4 80GB | $2.09/hr | $1.00–1.60/hr | $1.30–2.00/hr |
| H100 SXM5 80GB | $2.79/hr | $1.20–2.10/hr | $1.80–2.80/hr |
| 8× A100 SXM4 cluster | $16.72/hr | $7.20–12.80/hr | $9.00–14.00/hr |
Vast.ai's prices are set by individual hosts and fluctuate with market demand — sometimes cheaper than RunPod spot, sometimes more expensive. For consumer GPUs (RTX 3090, 4090), Vast.ai is often 10–20% cheaper. For data center GPUs (A100, H100), prices are comparable, with Vast.ai having better deals during off-peak hours.
Reliability: The Real Difference
This is where the platforms diverge significantly. RunPod manages its on-demand inventory more tightly — hosts must meet uptime requirements, and RunPod mediates disputes. RunPod spot instances can be interrupted, but on-demand instances run until you stop them. Reliability is generally high for established RunPod hosts.
Vast.ai is a true marketplace — anyone with a GPU can list it. Quality varies significantly by host. Before renting, you can see a host's reliability score (percentage of on-time availability), DLPerf score (GPU benchmark), and review count. Renting from hosts with 99%+ reliability and 100+ rentals is safe; renting from new hosts is a gamble.
GPU Selection
Both platforms have excellent GPU variety. Vast.ai has a slight edge on consumer GPU availability — you'll find more RTX 3080s, 3090s, 4080s, and even older V100s and P100s for ultra-budget workloads. RunPod tends to have better availability for high-end data center GPUs (H100 clusters) and more consistent instance specs.
- →RunPod: Better for H100 clusters, more consistent specs, better Serverless GPU product
- →Vast.ai: Better for ultra-cheap consumer GPUs, wider variety of older hardware
- →Both: Good A100 80GB availability, reasonable H100 single-GPU availability
- →Both: Support Docker templates, Jupyter notebooks, SSH access
Developer Experience
RunPod has invested heavily in its platform — the UI is polished, pod management is straightforward, and it has advanced features like serverless endpoints (pay only when requests come in), pod networking, team workspaces, and a template marketplace. For developers building production inference APIs, RunPod Serverless is a standout product.
Vast.ai's interface is more spartan but functional. The search/filter UI for finding instances is actually excellent — you can filter by GPU type, VRAM, price, reliability, location, disk speed, and more simultaneously. For GPU shopping, Vast.ai's search is arguably better than RunPod's.
Which Should You Use?
| Use Case | Best Choice | Why |
|---|---|---|
| Development & experiments | Vast.ai | Lowest cost, use spot instances freely |
| Fine-tuning with checkpointing | Vast.ai or RunPod spot | 40–70% cheaper than on-demand |
| Production inference API | RunPod Serverless | Pay per request, no idle billing |
| Long training runs (days) | RunPod on-demand | More reliable, SLA-backed |
| Budget-limited projects | Vast.ai | Often 20–30% cheaper for same GPU |
| Jupyter notebook workflow | RunPod | Better pod management UI |
| Consumer GPU (RTX 4090, etc.) | Vast.ai | More variety, often cheaper |
Most AI developers end up using both: Vast.ai for development and experimentation where cost matters most, RunPod for production serving and longer training runs where reliability matters. Creating accounts on both takes 5 minutes total and lets you pick the cheapest option for each job.