Namespace

Namespace — Fast microVM instances and CI runners with instant snapshots and cached builds. Namespace sells fast ephemeral compute, originally as a drop-in replacement for GitHub Actions runners and increasingly as general microVM instances with snapshotting and aggressive build caching. The API is infrastructure-shaped rather than agent-shaped, so it competes with Fly Machines rather than E2B. Teams already using it for CI can reuse the same instances for agent workloads without adding a vendor. Built by Namespace Labs. Founded 2022. Seed.

We track it in 1 comparison — Sandbox providers — so every claim below is a cell in a table you can open and check rather than an impression. Across those rosters it sits against 19 other tools, and what follows is where it visibly separates from them.

Where it wins.

• Snapshot & fork — Yes, which only 5 of 18 tools here manage.
• Idle cost — free-when-stopped, tied for best across 5 of 16 tools.

Each of those is ranked against the whole roster on its category page, not against a hand-picked subset, so a first place here means first of everything we list.

Where it gives ground.

• MCP server — No. Daytona records Yes.
• Meter — per-minute, 12th of 19. Cloudflare Sandbox records per-10ms.
• Runtimes — any-oci-image, 10th of 16. E2B records python, javascript-typescript, bash, any-oci-image.
• Funding — seed, 9th of 15. Fly.io Machines records series-c-plus.

None of these disqualify it on their own. They are the fields to check against your own requirements before you commit, because they are the ones where a competitor genuinely does better.

Provenance. 23 of 26 tracked fields carry a value for Namespace, and 3 of those cite a document you can open. Last verified 2026-07-23. Every figure keeps its own provenance — measured by us, claimed by the vendor, inferred, or community-reported — and we would rather print a dash than a guess.

Its nearest neighbour in our data is ascii. Namespace is ahead on Snapshot & fork (Yes against Partial) and Custom images (Yes against Partial). That pattern repeats across the rest of the roster — see Namespace alternatives for the other rivals, each compared the same way.

Company

Namespace Labs

Founded

2022

Funding

Seed

Fields we track

23 of 26

Last verified

2026-07-23

Sold to CI teams, useful to agent teams for the same reason: snapshotted microVMs with genuinely good caching. There is no agent SDK and no MCP server, so it competes with Fly rather than E2B — worth a look mainly if your builds already run here.

Cold start

1.5 s11th of 16

Inferred

Snapshot & fork

●Yes1st of 18

Vendor-claimedverified 2026-01-15source

Idle cost

free-when-stopped1st of 16

Inferred

MCP server

○No12th of 16

Inferred

Meter

per-minute12th of 19

Inferred

Isolation

microvm1st of 16

Vendor-claimedverified 2026-07-23source

Custom images

●Yes1st of 20

Inferred

Streaming output

●Yes1st of 16

Inferred

Namespace is the right call in these situations, each one drawn from a field we actually record:

• You already use Namespace for CI runners.
• Build-cache-heavy environments that are slow to reconstruct.
• You want infrastructure primitives rather than an agent SDK.
• Snapshot & fork is your binding constraint. Namespace records Yes, which only 5 of the 18 tools in the Sandbox providers roster do. We define that field as whether you can freeze a running sandbox and restore or clone it.
• Idle cost is your binding constraint. Namespace records free-when-stopped, the best figure in the Sandbox providers roster. We define that field as what you pay while a sandbox exists but is doing nothing — the common case when an agent is blocked on model inference.

Reach for something else when any of the following is a requirement rather than a nice-to-have:

• MCP server. Namespace records No on the Sandbox providers table. Daytona records Yes on the same field. If that is a hard requirement rather than a preference, start elsewhere.
• Meter. Namespace records per-minute, 12th of 19 in the Sandbox providers roster. Cloudflare Sandbox records per-10ms on the same field. If that is a hard requirement rather than a preference, start elsewhere.
• Runtimes. Namespace records any-oci-image, 10th of 16 in the Sandbox providers roster. E2B records python, javascript-typescript, bash, any-oci-image on the same field. If that is a hard requirement rather than a preference, start elsewhere.
• Funding. Namespace records seed, 9th of 15 in the Sandbox providers roster. Fly.io Machines records series-c-plus on the same field. If that is a hard requirement rather than a preference, start elsewhere.

We publish this block because a comparison that only lists what a tool is good at is marketing. Every figure above sits on the same page as its source, and the field definitions are on the category tables if you want to check how we measured them.

What we don't know. 3 of the 26 fields we track for Namespace are still blank: GPU, Price / hour and GitHub stars. Those render as dashes rather than as zeroes or assumptions, because an empty cell and a bad cell are not the same thing and only one of them is honest. If you know any of these figures and can point at a document, tell us.