Different categories entirely

Modal is sandbox infrastructure. It gives you an API to spin up isolated containers and run code. It's one building block in a much larger stack you'd need to assemble.

Runtime is the finished product. It combines sandbox orchestration, AI agent integration, a web UI with live preview, real-time multiplayer, git workflows, background agent pipelines, webhook integrations, team observability, and cost controls into a single platform. These aren't features you bolt on. They're deeply integrated systems that took thousands of engineering hours to build.

Sandboxes are one layer in a much larger stack

A sandbox API gives you a container. To get from "a container" to "a platform your team uses daily," you need to build and maintain at least eight separate systems on top: agent orchestration, live preview, git workflows, real-time collaboration, background agent pipelines, team observability, environment management, and auth/billing.

Each of those is a real engineering project with its own edge cases, failure modes, and ongoing maintenance. And the hard part isn't building them individually. It's making them all work together as one coherent product where a prompt triggers an agent, the preview updates live, a teammate sees the changes, the agent opens a PR, the cost gets attributed, and it all shows up in the team dashboard.

That's not a weekend project. That's a product company. And even if you built it, you'd be maintaining it forever while your competitors are shipping features.

Focus on your actual product

If you're a company that needs AI coding agents for your team, building a platform on top of Modal means becoming a platform company. Your engineers would spend months building infrastructure instead of shipping the product that makes your business money.

Runtime gives you the platform today. Your team starts building tomorrow.

It works for your entire organization

Modal is a developer API. Your PMs, designers, and growth team will never use it.

Runtime works for everyone. Non-engineers prompt Claude Code in natural language, see live preview, and ship with one click. Engineers import monorepos and run background agents. Same platform, no engineering gatekeeping.

The integration is the product

The value of Runtime isn't any single feature. It's how everything works together as one coherent system. The end-to-end flow from prompt to deployed software, with collaboration, visibility, and controls along the way, is what takes years to build and maintain.

You're building your own AI product and need raw compute infrastructure
You need GPU workloads for ML training or inference
You want full control over the container environment at the API level
You have a dedicated platform team to build and maintain the product layer

When Runtime makes sense

You want a complete platform for AI coding agents, ready to use
Your team (not just engineers) needs to build and ship with AI
You need live preview, multiplayer, background agents, git workflows, and observability working together
You'd rather ship product than build and maintain infrastructure

Ready to build with Runtime?

The complete platform for AI coding agents. No infrastructure to manage.

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Feature	Runtime	Modal
What it is	Complete platform for AI coding agents	Sandbox infrastructure (API/SDK)
Setup Required	None. Prompt and build.	Build your own UI, preview, orchestration
Live Preview	Built in, real-time	Build it yourself
AI Agent	Claude Code, Codex, Gemini CLI	Bring your own (no agent included)
Multiplayer Collaboration	Real-time, anyone on the team	Not included
Background Agents	Fire-and-forget from tickets	Build it yourself
Observability	Activity dashboard, cost tracking, spend controls	Basic compute metrics
Git Integration	Full (push, PR, branches)	Not included
Non-Engineer Access	PMs, designers, growth can use it	Developers only
GPU Compute
Custom Infrastructure	Managed or self-host	Full control over compute
Open Source