Comparison
Secure runtime for code-mode agents: Submilli vs E2B
E2B gives each agent session a full Linux microVM. Submilli executes agent-written programs in WebAssembly sandboxes and checks semantic permissions on covered operations.
A practical comparison
Product details are current as of November 3, 2026. Rows appear only where the cited public sources establish a comparison.
| Area | Submilli | E2B |
|---|---|---|
| What it is | A runtime for executing agent-written programs under explicit rules. | A cloud platform for giving each agent session a Linux microVM. |
| Isolation model | One WebAssembly sandbox for each program, with its own files and limits. | A Firecracker microVM with its own kernel per sandbox. |
| Access controls | Semantic permissions define allowed operations, resources, and argument values. | Network ingress and egress can be set under policy. |
| Where it runs | Runtime: self-hosted. Hosted cloud: operated by Submilli. Enterprise: your cloud. | E2B Cloud, BYOC in your AWS, GCP, or Azure account, or E2B Embed on your infrastructure. |
| License | Runtime: free, open source, Apache-2.0. | Runtime: Apache-2.0. |
| Pricing | Hosted cloud: freemium, usage-based. Enterprise: From $5,000/year, including BYOC and forward-deployed engineers. | Hobby is free with $100 usage credit; Pro is $150/month plus usage; Enterprise is custom plus usage. |
| Best fit | Code-mode agents that need permissions checked outside the model. | A full, isolated machine per agent session. |
Secure runtime for code-mode agents. Runtime is free, open source, and Apache-2.0. Hosted cloud is freemium and usage-based. Enterprise: From $5,000/year, including BYOC and forward-deployed engineers.
When to choose E2B
Choose E2B when a full Linux microVM, desktop, or shell environment is the work itself.
When to choose Submilli
Choose Submilli when the agent needs to call business operations under rules about the resource and arguments.
Runs are durable: after a restart they resume where they left off, without repeating finished steps.
Sources
Last checked .