E2B: Sandboxes for AI-Generated Code
Firecracker microVM sandboxes for code your agents wrote and nobody reviewed. It is not a development environment, it is unusually specific about its isolation boundary, and it is one of the few products here you can genuinely run yourself.
What It Is
An SDK that gives an AI agent a disposable, hardware-isolated computer
E2B provides sandboxes that a program creates on demand, runs code inside, and throws away. Its own description of the isolation is refreshingly concrete: each sandbox is powered by Firecracker, a microVM made to run untrusted workloads. The consumer is an application - an agent framework, an evaluation harness, a product feature that executes user or model-generated code - reached through an SDK rather than an IDE.
It belongs in this directory for the same reason Daytona does: people keep encountering it while shopping for cloud development environments and need to know quickly whether it is one. It is not. There is no per-developer workspace, no assigned machine, no persistent place for an engineer to work. If you are trying to get a team off local laptops, this is the wrong product and the tools comparison is the right page.
What makes E2B worth a page of its own is that it is the clearest example in this whole set of a vendor naming its isolation mechanism instead of describing it. "Secure sandbox" is marketing. "Firecracker microVM" is an architecture you can reason about, compare, and hold a vendor to. That specificity is the standard the rest of the category should be measured against.
Hardware-level separation
Firecracker gives each sandbox its own kernel behind a hypervisor, so a container escape is not the relevant threat model.
SDK-first
Sandboxes are created, driven, and destroyed from your own code. Lifecycle management is your responsibility, which is also where the cost control lives.
Open source and self-hostable
Apache-2.0, with a documented Terraform-based self-hosting path for Google Cloud and AWS. What is open is the infrastructure that runs the workload, not a client library, and that combination is close to unique across everything covered in this directory.
Who It Suits, and Who It Does Not
Excellent at one job, and genuinely wrong for the job most visitors to this site have
A good fit
- Products that execute code written by a model or submitted by a user, where hardware isolation is the requirement.
- Agent frameworks and evaluation harnesses that need many short-lived, concurrent sandboxes.
- Teams already using the OpenAI Agents SDK, which ships a hosted E2B sandbox client among its options.
- Organizations that must keep execution inside their own account, and are willing to operate the stack to do it.
- Anyone who wants a stated isolation mechanism they can put in front of a security reviewer.
A poor fit
- Teams wanting a cloud development environment for humans. There is no workspace product here at all.
- Long-running work. Session length is capped by plan, at one hour on the free tier and 24 hours on Pro.
- Non-engineering buyers. Adopting this means writing and maintaining integration code, not configuring a product.
- Agent work that is already safely contained by an existing CDE or CI runner, where a second vendor adds cost without adding protection.
- Teams that read "self-hostable" as low effort. Running a Firecracker fleet is real platform work with real headcount.
The question that sorts it
Ask who or what is at the keyboard. If a person is going to open an editor and work for six hours, you want a CDE. If a program is going to run code it generated moments ago, throw the machine away, and do that a thousand more times before lunch, you want a sandbox. Those two workloads have different units, different lifetimes, different cost curves, and different isolation requirements, and no product serves both well. Most confusion in this category comes from evaluating one against the other.
Deployment Model
Hosted by default, and genuinely self-hostable if you want it
| Concern | Hosted E2B | Self-hosted / BYOC |
|---|---|---|
| Infrastructure | E2B operates everything | Deployed with Terraform into Google Cloud or AWS, the only two targets the project documents. AWS is marked Beta. Azure and a generic Linux machine appear on the roadmap as unchecked items, not as documented paths. |
| Where code executes | E2B's environment | Your own cloud account or VPC |
| You operate | Your integration code and sandbox lifecycle logic | All of the above, plus the Firecracker fleet, capacity, upgrades, and incident response |
| If the vendor stops | Service ends | You hold Apache-2.0 source and a running deployment. This is a real continuity position, not a nominal one. |
That last row deserves emphasis because almost nothing else in this directory can claim it. Ona has no customer-managed control plane. Codespaces, Cloud Workstations, and Dev Box have no self-hosted form at all. Daytona's core development moved to a private codebase. E2B publishes its infrastructure under Apache-2.0 with a documented self-hosting path, which means the open-source claim survives the test that matters: could you keep running if the company stopped.
Do not mistake possible for easy. Operating a microVM fleet means capacity planning, kernel and hypervisor patching, network isolation, and being on call for it. The honest reading is that self-hosting is a genuine option for organizations with a platform team and a compliance reason, and an expensive detour for everyone else. Build vs buy works through whether you have that capacity.
License and Open Source Reality
Apache-2.0, and the open part is the part that runs the workload
What is open
The e2b-dev/E2B repository is Apache-2.0 and actively developed, and its README points to a self-hosting guide describing a Terraform deployment. The open component is the infrastructure itself, not a client wrapped around a closed service, which is the pattern that makes most open-source claims in this category hollow. Be exact about the reach, though: the infrastructure repository marks only Google Cloud and AWS as supported, with AWS flagged Beta, and the self-hosting guide documents only those two. Azure and a generic Linux machine are unchecked roadmap items.
What you still buy
The hosted service, its operational burden, its concurrency ceilings, and support. Open source does not make the commercial offering free; it makes the commercial offering optional, which is a different and more useful property.
Apply the durability tests anyway
A permissive license today is not a guarantee about next year. This is a single-vendor open source project, which makes it exactly as durable as the company's continued interest, and this category has produced two recent examples of what that looks like when interest fades. The mitigating factor is Apache-2.0 with no copyleft obligation and a working self-hosting path, so a fork is a practical option rather than a theoretical one. Check the license file on the default branch and its history yourself before relying on it - open source CDEs sets out the six tests worth running.
Pricing
A plan fee plus per-second usage, published in full - which is rare here
| Plan | Price, as of July 2026 | Limits |
|---|---|---|
| Hobby | Free, with a one-time $100 in usage credits and no credit card required | Up to 1-hour sandbox sessions, up to 20 concurrent sandboxes, 10 GiB free storage, community support |
| Pro | $150 per month, plus usage | Up to 24-hour sessions, up to 100 concurrent sandboxes with extra concurrency purchasable to 1,100, customizable sandbox CPU and RAM, 20 GiB free storage |
| Enterprise | Custom, not published | Negotiated, including deployment in your own AWS, GCP, or Azure account |
Usage rates, billed per second on both plans
| Resource | Rate | Notes |
|---|---|---|
| vCPU | $0.000014 per vCPU per second | Scales linearly with core count, from $0.000014 per second at 1 vCPU to $0.000112 at 8. Two vCPU is the default. |
| RAM | $0.0000045 per GiB per second | Configurable memory from 512 MiB to 8,192 MiB |
All plan and usage figures above are from E2B's own pricing page as of July 2026: e2b.dev/pricing. Enterprise pricing is not published.
Per-second rates are hard to feel, so convert them
Arithmetic on the published rates: $0.000014 per vCPU-second is $0.0504 per vCPU-hour, and $0.0000045 per GiB-second is $0.0162 per GiB-hour. A default 2 vCPU sandbox with 4 GiB of RAM therefore costs about $0.166 per hour, or roughly $0.0028 per minute - meaning a thirty-second agent task is a fraction of a cent.
That is the shape you want for bursty agent work, and it is also why the failure mode is different from a CDE's. Nobody overspends here by leaving one sandbox running. They overspend by shipping a loop that forgets to close them, at which point per-second billing across hundreds of concurrent sandboxes compounds quickly. Enforce lifetimes in your own code, alert on concurrent sandbox count, and treat the plan concurrency ceiling as a backstop rather than a budget. See FinOps and agent fleets.
Architecture and Isolation
The section that justifies the product existing separately from a CDE
Firecracker is a virtual machine monitor built for running many short-lived, minimal virtual machines with fast startup and low memory overhead. Using it means each sandbox gets its own guest kernel behind a hypervisor boundary rather than sharing a host kernel through namespaces and cgroups. For code nobody reviewed, that is a materially different guarantee: the attack surface is a narrow device model rather than the whole Linux syscall interface.
Why it beats a container here
A container escape is a known class of vulnerability with a steady supply of instances. A hypervisor escape is rarer and harder. When the code is adversarial by assumption, that difference is the entire argument.
Why not use it for everything
Session length caps, no persistent developer workspace, and an SDK rather than an IDE. The design that makes it right for disposable execution makes it wrong for a day of engineering work.
Isolation is not the whole threat model
A microVM stops code reaching the host. It does not stop code reaching the internet, exfiltrating a secret you injected, or burning your budget. Network egress policy and credential scoping remain your job.
Startup-time figures are vendor claims, and E2B contradicts itself on a single page. Both figures sit on the same e2b.dev homepage: one feature block says sandboxes in the same region as the client start in less than 200 ms, and another block on that same page says 80 ms. This is not two stale pages drifting apart over time - it is one page disagreeing with itself, which is a stronger reason to treat the number as marketing. No specific number is endorsed here, because the vendor does not present a single consistent one. If startup latency is load-bearing for your design, measure it yourself in your own region rather than citing either figure.
For the broader architectural picture, including how these choices compare to running agent workloads on your existing cluster, see microVM isolation, Kubernetes agent sandboxes, and CDE security.
Status and Durability
A young company with real distribution and an unusually good worst case
E2B is active, and it has the kind of validation that is hard to manufacture. On 04-15-2026, OpenAI's Agents SDK for Python shipped Sandbox Agents, a beta surface for running agents with a persistent isolated workspace, with hosted sandbox clients for seven providers: Blaxel, Cloudflare, Daytona, E2B, Modal, Runloop, and Vercel. Being one of seven first-party integrations in a widely adopted agent framework is meaningful distribution, and it makes the sandbox category itself look durable even if individual vendors are not.
Read that with appropriate care in both directions. It is a beta feature, and shipping alongside six competitors is evidence of a healthy market rather than of any single vendor winning it. Two of those seven are hyperscale platforms with effectively unlimited patience, which is the competitive pressure a startup in this position faces.
The risks, stated plainly
This is a young company in a market barely two years old, competing against hyperscalers, in a category that has already watched one participant abandon its original product and another get acquired. Enterprise pricing is unpublished, so total cost at scale is not knowable in advance. None of that is disqualifying; all of it belongs in the risk register.
Why the worst case is mild
Apache-2.0 source plus a documented self-hosting path means the failure mode is "we now operate this ourselves", not "we have to rebuild". Combine that with an abstraction over the sandbox interface in your own code - the create, execute, and destroy shape is broadly portable - and the exit cost is among the lowest in this directory.
Set against the rest of these six reviews, that contrast is the useful takeaway. Two products here cannot be self-hosted at any price, one has been placed in maintenance mode by its own vendor, one has an acquisition pending, and one moved its core development behind a private repository. A permissive license over the component that actually runs the workload is worth more than any feature comparison on this page. Vendor evaluation and build vs buy cover how to weigh it.
Related
The competing sandbox, and the CDEs this is not
E2B vs Daytona
The other agent sandbox vendor, on isolation, state, and how each one got here
Self-Hosted vs Managed
The framework for the CDE choice this product is not part of
Daytona
The closest competitor, with stateful fork and resume, and core development now behind a private repository
MicroVM Isolation
How Firecracker and its peers actually work, and when the extra boundary is worth its cost
Sandbox Environments
The category as a whole, and how to evaluate providers on isolation rather than adjectives
Kubernetes Agent Sandboxes
Whether your existing cluster can do this job, and what you give up if it does
Agent Fleets
Concurrency ceilings, lifecycle discipline, and keeping per-second billing from compounding
GitHub Codespaces
What to look at instead if you actually need a workspace for people
Open Source CDEs
The six durability tests to run before trusting any permissive license
Build vs Buy
Whether you have the platform capacity that self-hosting a microVM fleet actually requires
Sources and Citations
Every figure on this site with its publisher, date, and link