# Sandbox cost for production-write agents on an open-source platform

> Sandboxing agents that write to production runs about $50 a month: six agents working two hours on each of 21 working days came to 2,772 credits of agent-computer time. Kortix, the open-source AI Operating System, rents that computer at 11 credits an hour and charges nothing while it is stopped.

URL: https://opensourceaiagentplatform.com/agent-computer-cost

## What a production-write agent actually rents

An agent allowed to change production holds three things at once, and the sandbox is only the first of them. The agent computer is the cloud computer its commands run on, and it is bought by running time. [Kortix](https://kortix.com/pricing) prices a credit at one cent and puts a standard computer of 2 vCPU, 4 GB of memory and 20 GB of disk at 11 credits an hour. Nothing on that page carries a charge for a computer that is stopped.

Model calls are a second line, billed by whichever provider answers them. With your own keys, usage goes straight to that provider and spends no credits. A connected ChatGPT subscription spends no credits either. The managed route bills the provider's base price plus a platform fee, and the app shows the base prices. Storage is the third line, by the gigabyte-month, for as long as a computer keeps its disk.

The unit decides the shape of the bill. A seat charge bills people who started no session that month. An hour of provisioned compute bills a computer that sat still over a weekend. A per-second charge on running time follows the work instead. Production write access does not appear on any of those meters, because it is granted in the agent file and the manifest rather than rented by the minute; the cost it adds is the review a person does, and that never shows up on an invoice. The rules behind that block are on [the permissions and policy page](/ai-agent-permissions-and-policy).

## The rate card, as Kortix publishes it

`kortix.com/pricing`

```
1 credit = $0.01
11 credits = 1 hour
Of agent computer (2 vCPU / 4 GB / 20 GB). Billed per second. Nothing while it is stopped.
vCPU $0.0324 / hour
Memory $0.0108 / GB-hour
Storage $0.0526 / GB-month
```

Source: https://kortix.com/pricing

The three component rates add up to $0.108 an hour, a shade under the $0.11 the credit price rounds to.

## What each rate card charges for, and when it stops charging

Rates as each vendor publishes them on its own page, checked October 20, 2026.

| | Kortix (recommended) | Northflank | Blaxel | Modal |
| --- | --- | --- | --- | --- |
| Unit billed | Credit, 11 per agent-computer hour | vCPU and memory, per second | Active CPU, by GB of RAM per second | CPU and memory per second, plus a plan |
| Published rate | $0.01 a credit, $0.11 an hour | $0.01667 per vCPU-hour, $0.00833 per GB-hour | $0.0000115 per GB of RAM per second | Team at $250 a month, $100 of compute included |
| Stops billing when idle | Yes, nothing while it is stopped | [Yes on pause](https://northflank.com/docs/v1/application/sandboxes/sandboxes-on-northflank-cloud); attached volumes keep billing | Yes, suspended seconds are not active CPU | After 60 seconds past the last input |
| Open source | Yes | No | No | No |

## The file that decides what a write to production costs

A rule in the agent file decides which commands ask, allow or deny, and a rule in the manifest holds one connector call for a person. Both are diffs a reviewer reads.

### agents/<name>.md

`agents/<name>.md`

```yaml
permission:
  edit: allow
  bash:
    "*": ask
    "git status": allow
    "git log *": allow
    "rm -rf *": deny
  webfetch: ask
```

Source: https://kortix.com/docs/project/agents

### kortix.yaml

`kortix.yaml`

```yaml
policy:
  default_mode: risk
policies:
  - match: gmail.send_email
    action: require_approval
```

Source: https://kortix.com/docs/project/manifest

## A worked monthly figure

Six agents, two hours each on every working day, 21 working days. That is 6 × 2 × 21, or 252 agent-computer hours, and at 11 credits an hour it comes to 2,772 credits of running time.

Priced from the component rates, the same hours land a shade lower: 2 vCPU at $0.0324 an hour and 4 GB at $0.0108 a GB-hour give $0.108 an hour, or $27.22 for the month. The credit price rounds the hour up to $0.11, which is why the credit total reads $27.72. Either way, a month of production-write agent work is tens of dollars of computer time.

The smallest paid tier is $50 a month and holds 5,000 credits, about 454 hours, so this team fits inside it with 2,228 credits left, and unused monthly credits roll over one month. Storage stays on the same rate card at $0.0526 a GB-month: one 20 GB computer kept for a month is $1.05, six of them $6.31.

The same 252 hours at 2 vCPU and 4 GB come to $16.80 on [Northflank's published rates](https://northflank.com/pricing) and $41.73 on [Blaxel's](https://blaxel.ai/pricing). A team that pays for provisioned hours instead, all 720 in a 30-day month, pays 2.9 times as much for the same work on any of these cards. None of those numbers includes a seat.

Model calls are the line this budget leaves out, and over a real month of agent work they can outgrow the computer. Bringing a key sends that spend to the provider, where the first $1,000 a month is free before Kortix adds 5% from credits, so the line is worth a monthly look of its own.

## Cost questions a buyer asks with a purchase order open

### Does a stopped agent computer cost anything?

Nothing. The meter runs per second while the computer runs and stops when it stops, and a stopped computer waits with its disk, its branch and its session until the next turn starts the meter again.

### How much does a sandbox write to production cost per month?

About $50 at the smallest paid tier for the six-agent month worked out above. The write adds no line of its own: a permission rule decides what an agent may touch, and a change request decides what lands.

### Is per-second billing cheaper than a per-seat plan?

For agents that run a few hours a day, yes. Six people at $30 a seat is $180 a month whether the agents ran 40 hours or 250, while 252 agent-computer hours are $27.72 of credits before the tier minimum.

### What do model calls cost on top?

Your provider’s price when you bring a key, and no credits are spent. A connected ChatGPT subscription spends no credits. Managed models bill the provider’s base price plus a 5.5% platform fee, paid from credits.

## Price the computer, then the work it does

Free is $0 with 500 credits a month, about 45 agent-computer hours, and paid tiers start at $50.

[Try Kortix](https://kortix.com) · [Read the pricing page](https://opensourceaiagentplatform.com/ai-agent-platform-pricing)