AI Development Services in 2026: Which Layer You Actually Need
AI development infrastructure splits into four layers: sandboxed code execution (E2B, Pro $150 a month), durable workflows (Temporal, free to self-host, Cloud from $50 per million Actions), prompt testing (PromptFix, from $9 a month) and API governance (Treblle, Core $233 a month billed yearly).
The short version
Buy one layer at a time, the one whose failure you have already hit: a sandbox like E2B for agent-run code, Temporal for jobs that must survive a crash, PromptFix for prompts that change weekly, Treblle once outsiders call your API. Prices were re-read from each vendor in November 2026.
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In this guide9 sections
Start with E2B if your agent runs code nobody reviewed, or with Temporal if a long job dies when a server restarts. Most teams shipping a first agent need one infrastructure layer, not four: the one whose failure they have already hit. The other two layers, prompt testing and API governance, usually come later.
Hokai chart of the four infrastructure layers and the failure that tells you that you need each one, from the vendors' own pages as checked on 15 November 2026.
The shortlist and what each costs
| Layer | Example | Entry price | You need it when |
|---|---|---|---|
| Sandboxed code | E2B | Free, Pro $150/mo | An agent runs code |
| Prompt testing | PromptFix | Free, Starter $9/mo | Prompts change often |
| Durable workflows | Temporal | Free self-host | Jobs must survive a crash |
| API governance | Treblle | Core $233/mo, yearly | Outsiders call your API |
Prices are from each vendor's pricing page, read on 15 November 2026, except Temporal's, read on 12 November 2026.
- E2B Pro a month
- $150
- Plus usage billed by the second
- Temporal Cloud per million Actions
- $50
- No base fee
- Treblle Core a month
- $233
- Billed yearly
- PromptFix Starter a month
- $9
- Free plan below it
How to choose which layer you need first
Ask four questions, in this order, and stop at the first yes.
Does an agent execute code nobody has reviewed? A coding copilot, a data-analysis agent or anything that runs shell commands for a user needs somewhere to do it safely.
Does a workflow need to survive a crash? Payment retries, order pipelines and long agent jobs share one need: if the server restarts mid-step, the work resumes where it stopped instead of vanishing.
Do prompts ship more than once? A prompt that scored well in a demo can degrade when the vendor updates the model behind it, or when a teammate edits it without testing against the old version.
Does anyone outside your team call your API? An internal endpoint can live on ad hoc logs. Once a paying customer or an auditor depends on it, you need live monitoring and documentation that keeps up with the code.
- E2B
- Hobby plan, $100 one-time credit
- Temporal
- self-host the MIT-licensed server
- PromptFix
- free plan, 15 improvements a month
- Treblle
- sign-up needs no card, no free plan listed
When the agent runs code: sandboxes
E2B runs every sandbox in its own Firecracker microVM, the isolation layer AWS built for Lambda, so agent code cannot reach the host or another customer's session. Insight Partners, which led its $21M Series A in July 2025, said 88% of Fortune 100 companies were running E2B sandboxes at the time.
Its pricing page, read on 15 November 2026, lists three plans:
| Plan | Price | Sessions | Concurrent |
|---|---|---|---|
| Hobby | Free, $100 credit | 1 hour | 10 |
| Pro | $150/mo + usage | 24 hours | 100 |
| Enterprise | From $2,000/mo | Multi-day | 500+ |
On Pro, add-ons raise concurrency to 600 or 1,100 sandboxes. Enterprise adds deployment in your own cloud. The limit to know: on Pro a sandbox still ends at 24 hours, so an agent that must stay alive for days needs the contract tier or another design.
Two other names come up in the same search. Modal runs sandboxes alongside GPUs and general serverless jobs, and Daytona is the other dedicated sandbox runtime agent builders compare. Inngest now includes 100 concurrent sandboxes in its $99 Pro plan, which saves a second vendor if your jobs already run there.
When a job must survive a crash: durable workflows
Temporal records every step of a workflow so it can pause for months and continue after a worker crashes. The server is open source under the MIT licence and free to self-host, with SDKs for Go, Java, Python, TypeScript, .NET, Ruby and PHP.
Temporal Cloud, the managed service, has no base fee. Its pricing page, read on 12 November 2026, charges $50 per million Actions, falling to half that past 100M Actions a month, plus storage.
New accounts get $150 in credits. Self-hosting trades that bill for the work of running a distributed system yourself.
The company raised a $300M Series D at a $5B valuation in February 2026, led by Andreessen Horowitz, according to its own announcement.
When prompts keep changing: prompt testing
PromptFix scores a prompt for clarity and structure and runs it against several models side by side, so a change that breaks the output shows up before release. The plans as PromptFix listed them on 15 November 2026:
| Plan | Price | Models compared |
|---|---|---|
| Free | $0 | Not listed |
| Starter | $9/mo | Up to 3 |
| Pro | $29/mo | Up to 4 |
| Teams | $12/seat, 5 seats min | Pro-level |
It checks prompts before they ship. It does not watch what users do with the output in production; that is the evals and observability layer, covered in the three jobs hiding inside agent observability.
When outsiders call your API: governance
Treblle sits in front of an API through one SDK and turns its live traffic into monitoring, analytics and documentation. Its pricing page lists Core at $233 a month, billed yearly, for up to 5 APIs and 500 requests a minute.
Growth is custom-priced and adds API security scanning; Enterprise adds governance, compliance, SSO and self-hosting. If compliance flagging is the reason you are buying, budget for Enterprise, not Core.
The comparisons people actually search for
Temporal or Inngest? Temporal suits a multi-language backend that wants full control and can run it, or pay per Action on Temporal Cloud. Inngest is built for TypeScript on serverless hosts: its free plan covers 50,000 executions a month and Pro starts at $99. For a side-by-side of Inngest and its closest rival, see Trigger.dev vs Inngest.
E2B or an AI code editor? This is a category error. An editor such as Cursor or a workspace such as Replit is where a person writes code; E2B is the runtime an agent calls to run code with no person in the loop.
Treblle or Postman? Postman is for building and testing requests by hand during development. Treblle watches live production traffic. Teams that need both keep Postman for building and add Treblle once the API ships.
Who does not need any of this yet
A founder still testing an idea gets little from these four today. With one engineer and few users, retry logic, a cron job and plain logs cover the failures you will meet. Buying a layer before its failure has happened is how a small team ends up with four vendor bills and no users.
The case against buying any of this
You can build each layer yourself with a message queue, a scheduler and the logging you already pay for, and many small teams do for years. The case for buying starts when your engineers spend more hours keeping the home-made version alive than the vendor's invoice would cost. Until then, the free ways in listed above are enough to prove a prototype. If you are still unsure which tools fit your stack, Smart Match asks a few questions and returns a shortlist.
Frequently asked questions
Which AI infrastructure layer should a team buy first?
The one whose failure you have already hit. A sandbox such as E2B when an agent runs code nobody reviewed, durable execution such as Temporal when long jobs die on a restart, prompt testing when prompts change weekly, and API governance once outside customers call your API.
How much does E2B cost?
Hobby is free with a one-time $100 usage credit and 10 concurrent sandboxes. Pro is $150 a month plus per-second usage, with 24-hour sessions and 100 concurrent sandboxes. Enterprise starts at a $2,000 monthly commit, per E2B’s pricing page read on 15 November 2026.
Is Temporal free?
The Temporal server is open source under the MIT licence and free to self-host. Temporal Cloud has no base fee and charges per Action, from $50 per million, with $150 in credits for new accounts, per its pricing page read on 12 November 2026.
Should I pick Temporal or Inngest?
Temporal fits a multi-language backend that wants to self-host or pay per Action on Temporal Cloud. Inngest fits TypeScript teams on serverless hosts: its free plan covers 50,000 executions a month and Pro starts at $99.
Does Treblle have a free plan?
Its pricing page no longer lists one. The first listed plan is Core at $233 a month, billed yearly, for up to 5 APIs; security scanning is on Growth and compliance on Enterprise, both custom-priced.
Covered in this guide
- E2B: Enterprise sandbox infrastructure for AI agents to execute code securely. Firecracker microVMs, sub-second cold starts, Python and JavaScript SDKs. Free tier with $100 credit; paid plans scale up to enterprise BYOC deployment.
- PromptFix: AI prompt reliability platform that scores prompts 0-100, versions history, and runs A/B tests across GPT-4, Claude, and Gemini. Pro plan at $29/month.
- Temporal: Open source (MIT) durable execution platform for resilient workflows as code. Self-host free, or use Temporal Cloud with pay-as-you-go pricing and no base fee.
- Treblle: API observability platform that monitors, documents and governs APIs from their live traffic; paid plans start with Core, billed yearly.
- Inngest: Inngest runs event-driven background jobs and AI workflows with no queue or worker fleet to manage. A Free plan that needs no credit card covers development and small production apps.
- Cursor: Cursor is an AI code editor built on VS Code, widely adopted across large enterprise engineering teams, with Agent Mode, Tab completion, and Cloud Agents.
- Daytona: Per-second billed sandboxes for AI agents, in US and EU regions, with GPU and Windows options and $200 of starter credit; the core repo went private in 2026.
- Modal: AI infrastructure that developers love: serverless compute for ML inference, training, and batch processing
- Replit: Cloud coding environment where you describe an app in plain English and AI builds and deploys it.
Sources
Still deciding?
This guide covers a handful of options. Smart Match checks every listing in the directory against how you actually work and what you can spend, then hands you the shortlist and the reason behind each pick.
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