The AI developer cloud for GPU pods, serverless inference and clustering

The durable AI runtime that runs in your cloud, not ours
Estimated monthly website visits
Similarweb estimates for this domain, not active users. Only available observation months are shown; collection date is separate from the traffic period.
Collected Nov 11, 2026

This is our editors' assessment out of 5, not an average of user ratings. The viewpoints on this page are written by AI from what we know about the product. They are not customer reviews.
According to OpenAITools.app telemetry verified on 2026-11-11, Union.ai (union.ai) is an AI platform indexed under AI Developer Tools generating 17.79K monthly visits with a month-over-month traffic delta of -7.04K (-28.4%). Its primary geographic market is United States (52.8% traffic share), and it operates on a Freemium, Contact for Pricing pricing model. Top competing alternatives by monthly volume include RunPod (2.88M visits/mo), Vast.ai (1.26M visits/mo), Modal (1.2M visits/mo).
Durable execution saves us countless hours of pipeline debugging.
Flyte integration makes scaling agent workloads seamless.
Great control plane for cloud-native ML infrastructure.
Resuming failed GPU runs without restarting is a lifesaver.
AI-synthesized perspectives grounded in live site inspection, pricing structure, and category benchmarks — presented as editorial viewpoints rather than individual customer testimonials.
Tasks, traces and artifacts survive infrastructure failure. Runs fork, recover and replay from the last good step instead of starting over, with retries and caching handled by the runtime.
Named, typed and versioned artifacts wire teams together, with lineage showing which run produced each version and which downstream tasks consume it.
Run the control plane in Union's cloud while workloads execute on clusters in your AWS, GCP, Azure or neocloud account, under your own security perimeter.
Bring OpenAI, Claude, PydanticAI or CrewAI agents; each turn is traced and sandboxed in ephemeral containers, MCP servers and human approvals supported.
One gateway for hosted LLM providers and self-hosted vLLM, SGLang or Ollama endpoints, with virtual keys, budgets, guardrails and per-GPU observability.
Priority, concurrency, quotas and cluster selectors on queues, so backfills never steal capacity from production training or serving jobs.
Union.ai grew out of the Flyte project, the open-source workflow engine used widely for data and ML pipelines, and it keeps that lineage in its design: you write ordinary Python tasks and task environments, and the runtime takes care of scheduling, caching, retries and typed data passing between steps. What Union adds on top is durability. If a run dies because a node disappears, a GPU is reclaimed, an API returns a 429 or an out-of-memory kill fires, the run is recovered and continues from the failed step rather than the beginning of the pipeline.
The current platform is organised around a handful of capabilities. The AI factory manages named, versioned artifacts so a checkpoint or dataset has a traceable producer and consumers, which matters for reproducibility. Production agents let teams keep the agent framework they already use, including OpenAI, Claude, PydanticAI and CrewAI, while making every turn of the loop durable, traced and sandboxed. The inference gateway puts external model APIs and self-hosted vLLM, SGLang or Ollama endpoints behind a single governed interface with virtual keys, budgets and guardrails. Around these sit scheduling primitives such as priority queues, concurrency limits, quotas and cluster selectors.
Deployment is deliberately bring-your-own-cloud. Union hosts the control plane, which stores references and metadata rather than payloads, while your data, models and compute stay inside your own perimeter, so your negotiated cloud rates and credits still apply. Union is available on AWS Marketplace and through self-service signup, with an optional managed-cluster service billed per cluster.
Train and fine-tune models across multiple nodes with automatic recovery from preemption, plus reproducible checkpoints wired through versioned artifacts.
Serve vLLM, SGLang or Ollama endpoints and hosted model APIs through one gateway with budgets, virtual keys and per-GPU metrics, scaling to zero when idle.
Build data factories on plain Python: ingest structured and unstructured data, schedule by artifact triggers, and keep lineage from raw inputs to finished models.
Run multi-step agents in production with durable loops, traced turns, sandboxed code execution and human approval steps.
Side-by-side telemetry comparison of competing AI tools in the same primary category
| Rank | AI Tool | Monthly Visits | MoM Growth | Direct traffic share | Pricing | Head-to-Head |
|---|---|---|---|---|---|---|
| ● | Union.ai | 17.79K | -28.4% | 40% direct | Freemium, Contact for Pricing | Current |
| 1 | RunPod | 2.88M | +5.9% | 57% direct | Paid | vs RunPod |
| 2 | Vast.ai | 1.26M | +2.8% | 75% direct | Paid | vs Vast.ai |
| 3 | Modal | 1.2M | +30.2% | 71% direct | Freemium, Contact for Pricing | vs Modal |
| 4 | Lightning AI | 272.56K | -12.3% | 52% direct | Freemium, Paid, Contact for Pricing | vs Lightning AI |
| 5 | Nebius | 1.15M | +10.7% | 39% direct | Paid, Contact for Pricing | vs Nebius |
| 6 | Metaflow | 15.28K | -18.1% | 40% direct | Free | vs Metaflow |
The AI developer cloud for GPU pods, serverless inference and clustering
Rent cloud GPUs by the second from a global marketplace
Rent cloud GPUs by the second from a global marketplace
Serverless cloud infrastructure for AI and data workloads
Serverless cloud infrastructure for AI and data workloads
The AI cloud built by the creators of PyTorch Lightning
An AI-native cloud built from silicon to API for training, tuning, and serving models
An AI-native cloud built from silicon to API for training, tuning, and serving models

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Together AI is the AI Native Cloud — a full-stack platform for running, fine-tuning and training open-source models. It spans serverless inference APIs, dedicated endpoints, GPU clusters, post-training and storage, all backed by in-house systems research.
Together AI is the AI Native Cloud — a full-stack platform for running, fine-tuning and training open-source models. It spans serverless inference APIs, dedicated endpoints, GPU clusters, post-training and storage, all backed by in-house systems research.