If your main requirement is GPU inference endpoints that automatically scale with traffic, including down to zero when idle, I’d shortlist Modal, Replicate, and Google Cloud Run. AWS SageMaker is also viable, particularly if you’re already deep in AWS.
My pick: Modal
Modal Inference is probably the best fit if you're building a custom inference service rather than simply exposing an existing model.
Why Modal: its inference infrastructure explicitly supports elastic GPU autoscaling down to zero, and its autoscaler exposes controls such as minimum/maximum containers, target concurrency, scale-up windows, and scale-down windows. Modal also offers GPU snapshotting and model/weight caching aimed at reducing cold-start latency.
One important caveat: scale-to-zero means cold starts. Modal's serverless HTTP servers can return a 503 while the first container is starting after being at zero, so your client/load balancer needs appropriate retries.
When I'd choose the others
Replicate is attractive if you want the least infrastructure work. Deployments can automatically scale from zero to hundreds of instances based on traffic, with configurable minimum/maximum instances and hardware.
Cloud Run is particularly compelling if you already have a Dockerized inference server. GPU-backed Cloud Run services can scale to zero, and its autoscaler scales based on request concurrency/CPU rather than GPU utilization. That latter point means you'll need to tune concurrency carefully for GPU workloads.
SageMaker Serverless Inference is convenient if you're already on AWS. AWS manages the scaling and automatically brings serverless endpoints down to zero when idle. However, the serverless option has limits such as 4 MB payloads and 60-second processing time, which can make it unsuitable for larger/longer-running LLM inference. docs.aws.amazon.com AWS also supports scale-to-zero with asynchronous inference for workloads where requests can be queued.
Bottom line
For a new inference API, I'd generally evaluate them in this order:
Modal → Replicate → Cloud Run → SageMaker
The deciding variable is really cold-start tolerance. If your endpoint must respond in tens of milliseconds even after long idle periods, true scale-to-zero isn't compatible with that requirement; you'd keep at least one warm replica. If a few seconds of startup latency is acceptable for occasional traffic, scale-to-zero can substantially reduce idle GPU cost.
If you tell me what model you're serving (e.g. Llama, Whisper, Stable Diffusion), GPU size, expected requests/sec, and acceptable cold-start latency, I can do a concrete Modal vs. Replicate vs. Cloud Run cost/architecture comparison.
When choosing a serverless platform that scales to and from zero for AI inference, the decision usually comes down to whether you are running standard CPU-bound models or heavy GPU-accelerated deep learning models (like LLMs or stable diffusion).
The top-tier specialized platforms for serverless GPU/CPU inference with scale-to-zero capabilities balance cost-efficiency, cold-start times, and developer ergonomics:
Modal – Best for developer-first Python/GPU workflows. Modal is a general serverless compute platform that treats AI inference as a first-class citizen. It scales seamlessly to and from zero, bills precisely per second, boasts some of the lowest raw GPU rates on the market (e.g., A100/H100), and lets you define infrastructure purely via a Python SDK.
Baseten – Best for production-grade model serving. Baseten is purpose-built for high-performance ML inference, offering robust auto-scaling to zero, optimized model runtimes (like vLLM), fast cold starts, and explicit controls over concurrency and replica counts.
Replicate – Best for pre-packaged or fast-to-deploy models. If you want to run open-source models with zero infrastructure management or deploy custom weights into an established ecosystem with pay-per-second scaling to zero, Replicate abstracts away almost everything.
Cerebrium – Best for ultra-low latency cold starts. Cerebrium focuses heavily on optimizing serverless GPU infrastructure (using snapshot restores and optimized container caching) to minimize the dreaded cold-start lag when scaling up from zero.
Standard Hyperscalers (AWS Lambda / Google Cloud Functions) – Best if your inference is lightweight and strictly CPU-bound (e.g., scikit-learn, small NLP pipelines). For heavy LLMs or computer vision, they lack the native, cost-effective GPU scale-to-zero agility of dedicated AI platforms.
To help narrow down the ideal platform, tell me:
What framework or model are you deploying (e.g., Llama 3, a custom PyTorch model, or a small CPU model)?
What are your expectations for cold-start latency tolerance?
Are you looking for a pure API service or a custom container environment?
If you're looking for serverless model inference that scales to zero when there is no traffic, you have several good options. The key distinction is whether you want a managed API for deploying your model, a serverless GPU platform, or a cloud-native serving stack.
Scale-to-zero means you stop paying for idle inference compute when there are no requests, then provision capacity again when traffic returns. The trade-off is cold-start latency: the platform may need to allocate a GPU, load model weights, and initialize the runtime before serving the first request.
The main options
1. Runpod Serverless
(Best for flexible GPU inference)
Deploy custom containerized models behind an API, with GPU workers that scale to zero. A good fit for open-source LLMs, image generation, and custom PyTorch or vLLM deployments. It also offers per-second billing.
Trade-off: You manage more of the model-serving container and worker configuration than with a fully managed model API.
Run your own HTTP inference server in a container. Cloud Run supports GPU-backed services that can scale to zero, as well as CPU-only workloads. It's especially appealing if you already use Google Cloud and want to deploy a standard container without managing Kubernetes.
Trade-off: GPU availability, instance limits, startup behavior, and request concurrency need to be checked against your model and region.
A strong option when your model is on the Hugging Face Hub. You get managed model deployments, configurable hardware, autoscaling, and scale-to-zero after inactivity. Hugging Face documents a default one-hour idle timeout.
Trade-off: Scaling from zero can take minutes for some models, and the proxy can return HTTP 503 while a replica initializes unless you configure request waiting appropriately.
A good fit for intermittent inference workloads in AWS. Managed serverless endpoints scale down to zero, with pay-per-use billing. For long-running or large-payload jobs, SageMaker Asynchronous Inference can queue requests and scale instance capacity down to zero.
Trade-off: Check supported model artifacts, memory and payload limits, concurrency, and whether the serverless endpoint's constraints fit your model.
Define your inference service in Python, choose GPU hardware, and deploy custom models or serving engines such as vLLM and SGLang. Modal supports scale-to-zero and offers managed inference endpoints.
Trade-off: You will work with Modal's programming model and deployment abstractions rather than a completely cloud-agnostic interface.
A convenient option for serving open-source or custom models through an API, particularly image, video, and generative AI workloads. Its deployments support autoscaling from zero and configurable GPU hardware.
Trade-off: Evaluate its model packaging, prediction lifecycle, and pricing against your desired serving architecture.
Python-native development and custom inference logic
Modal
A model already on Hugging Face
Hugging Face Inference Endpoints
Minimal infrastructure management in Google Cloud
Cloud Run
Existing AWS infrastructure and managed ML workflows
Three things to verify before committing
Actual scale-to-zero behavior. Some products offer a true zero-worker configuration, while others have minimum-instance settings or separate modes for keeping capacity warm.
Cold starts and request handling. Find out whether the first request waits, gets queued, or receives an error while the model starts. This can matter more than raw inference latency.
Total cost. Include GPU runtime, startup overhead, storage, networking, and any per-request or per-token charges. Scale-to-zero doesn't necessarily mean every associated resource is free.
Let’s narrow it down
I can recommend a much more specific architecture if I know what you're serving.
Modal, Cerebrium, and RunPod Serverless are the leading serverless inference platforms that support fine-tuned model deployment with true auto-scaling to zero and GPU acceleration.
The choice of platform depends on your specific infrastructure preferences, custom code requirements, and scaling speed needs.
Scales to zero; fast worker startup using template network volumes
Budget-conscious teams wanting simple webhook/API queue scaling
Platform Breakdown
Modal: Excellent for custom fine-tuned weights (e.g., custom PyTorch/Safetensors checkpoints or LoRA adapters). It lets you define infrastructure using a standard Python decorator, handling scale-to-zero and concurrency natively without heavy YAML configurations.
Cerebrium: Specifically built for production-grade ML workflows. It optimizes fine-tuned models automatically, manages fast scaling to zero, and integrates smoothly with logging, monitoring, and secrets management out of the box.
RunPod Serverless: Provides cheap, scalable serverless endpoints via a network worker architecture. When a request comes in, it spins up a pod from zero, processes the queue, and scales back down to zero to eliminate idle GPU costs.
To help narrow down the ideal platform, tell me:
What framework and size is your fine-tuned model (e.g., Llama-3-8B LoRA, custom PyTorch)?
For a fine-tuned model that you own and need to serve behind an API with autoscaling all the way to zero, I’d start with Modal.
My shortlist
Platform
Scale to zero
Custom/fine-tuned models
Cold-start story
Best fit
Modal
✅
✅
Excellent; memory/GPU snapshots
SageMaker Serverless Inference
The simplest path to a hosted generative-model API
Replicate
Best default for a Python team
RunPod Serverless
✅
✅
Very good
Lowest-cost / maximum GPU flexibility
Replicate Deployments
✅
✅
Good, but model startup can matter
Easiest API/product integration
Baseten
✅
✅
Good with warm replicas
Production ML platform / enterprise
Why Modal: its serverless functions scale to zero by default, can scale to 1,000+ GPUs, and Modal specifically supports memory/GPU snapshots to reduce the cold-start penalty of loading large models.
For a custom model, you can essentially package your inference code and weights in Python rather than adopting a specialized serving format. That's particularly attractive if you're already using Hugging Face Transformers, PyTorch, vLLM, etc.
RunPod is the alternative I'd benchmark if GPU cost and hardware choice dominate. Its Serverless product uses containers and supports scale-to-zero, while also giving you a relatively straightforward path to move the same container onto persistent GPU infrastructure later.
Replicate is compelling if you want the least infrastructure-facing experience: its Deployments explicitly support custom models, automatic scaling from zero, configurable min/max instances, and private dedicated endpoints. replicate.com One caveat: with deployments, you're charged while instances are setting up/idle as well as while processing, so scale-to-zero doesn't necessarily mean "pay only for inference execution."
What I'd choose
Python/ML engineering team → Modal
Cost-sensitive + comfortable with Docker → RunPod
Want a model API with minimal infrastructure work → Replicate
Need a more managed production serving/MLOps experience → Baseten
One important qualification: scale-to-zero is only attractive if your traffic is bursty enough to tolerate cold starts. For a continuously busy model, keeping one or more replicas warm can be both faster and economically preferable.
If you tell me model size (e.g. 7B/70B), GPU requirement, expected requests/sec, and latency target, I can do a more concrete Modal vs RunPod vs Replicate cost/architecture comparison for your workload.