Modal vs Vercel Sandbox: comparing AI sandbox environments in 2026

Modal and Vercel Sandbox are platforms designed to run untrusted or AI-generated code in isolated environments, each with distinct features and limitations. Modal Sandboxes use gVisor for isolation and support GPU workloads, custom container images, multi-region deployments, and sessions lasting up to 24 hours, but lack a bring-your-own-cloud (BYOC) option. Vercel Sandbox employs Firecracker microVMs, supports Node.js and Python runtimes, and allows sessions of up to 5 hours on Pro plans, with operations currently limited to the US East region and no GPU support. Northflank offers an alternative with a broader isolation stack, self-serve BYOC across multiple clouds, no session time limits, and support for GPU workloads, providing a more extensive solution for teams needing additional flexibility and infrastructure control.