Agent runtime cost: what four vendors bill. Kortix is open source.
Agent runtime cost comes down to two numbers: the rate a vendor charges and how long it bills a session. Four runtimes price the same hour differently. Kortix is the open-source AI Operating System, and the paid plan is credits: 25 tiers from $50 a month (5,000 credits) to $50,000 a month (5,000,000 credits), at 100 credits per dollar.
What the pricing page says
20,000 credits / month
$200 a month ≈ 1,830 hours
11 credits = 1 hour
Of agent computer (2 vCPU / 4 GB / 20 GB).The plan line and the credit rate on kortix.com/pricing, at the $200 tier.
Source: kortix.com/pricing
The unit each vendor bills
Every agent runtime bill is a rate multiplied by a unit, and the units are not interchangeable. Amazon Bedrock AgentCore prices per second of actual CPU and memory, with a one-second minimum. E2B bills sandboxes per second of running time. Daytona lists vCPU at $0.0504 an hour and memory at $0.0162 per GiB-hour. Modal bills while the container processes, starting the meter during application load.
On Kortix the paid plan is credits: 25 tiers from $50 a month (5,000 credits) to $50,000 a month (5,000,000 credits), at 100 credits per dollar. A unit tells you how the meter ticks. The session tells you how long it ticks.
What ends a session
| Product | Unit billed | What ends a session |
|---|---|---|
| Kortix | Credits on the agent computer, at 100 credits per dollar | 15 minutes after the last turn, or you stop it |
| Amazon Bedrock AgentCore | Per second of CPU and memory, one-second minimum | Session termination; idle memory reclaimed after 120 seconds |
| E2B | Per second of running sandbox time | Hobby at 1 hour, Pro at 24 hours |
| Modal | Compute while the container processes, load included | The container stops processing |
The third column is the part most pricing pages leave out. AgentCore keeps a Runtime session alive from microVM ready through initialization, active processing and idle periods until the session terminates, reclaims idle memory after 120 seconds in Runtime v2, and lets sessions last "up to 8 hours for each lifecycle on microVMs, or up to 14 days on Instances". E2B ends a Hobby session at one hour and a Pro session at 24 hours. Modal's meter stops when the container stops processing. On Kortix an idle computer stops about 15 minutes after its last turn, so the meter ends when the work does.
Three things that move a monthly bill
Session lifetime. A per-second rate says nothing about how many seconds arrive. An AgentCore session can stay open for up to 8 hours for each lifecycle on a microVM, or up to 14 days on the Instances compute type, as the AgentCore session docs put it, and each wake-up inside that window is billable while the CPU is active, with memory billing until the reclaim. E2B's one-hour Hobby cap turns that risk into a ceiling, and the 24-hour Pro cap lifts the ceiling to a day.
Concurrency. Each running session is its own meter. One isolated sandbox per session. Each session has its own isolated machine and branch. Ten agents working at once are ten agent computers billing at once. The number of sessions open at 3 a.m. matters more than the published rate.
Who stops the agent computer. A vendor cap, an idle reclaim or a stop command decides when the meter ends. Kortix stops an idle agent computer about 15 minutes after its last turn, and a running turn holds it for four hours. You can stop it sooner. E2B's plan caps end the session for you. AgentCore ends a session at termination, and idle memory is reclaimed after 120 seconds in Runtime v2.
One hour on a 2 vCPU machine
Three of these meters can be priced for the same hour from the published numbers. Kortix: 11 credits an hour on a 2 vCPU / 4 GB / 20 GB agent computer, at 100 credits per dollar, or $0.11. E2B: the default 2 vCPU / 4 GiB sandbox bills $0.000028 a second for vCPU and $0.0000180 a second for its 4 GiB of memory, so the pair comes to $0.000046 a second, about $0.17 an hour. Daytona: two vCPU at $0.0504 an hour plus 4 GiB at $0.0162 per GiB-hour, or $0.17.
The three hourly rates land within six cents of each other, at $0.11, $0.17 and $0.17. The rules that decide how many hours get billed are where the invoices separate.
Kortix sells credits in 25 tiers, from $50 a month (5,000 credits) to $50,000 a month (5,000,000 credits), at 100 credits per dollar, so the arithmetic above holds at every tier. Self-hosting removes the Kortix credits meter. Run it on Kortix Cloud, in your VPC, or on your own on-prem network. Self-host is free, and the session machine does not move with it: sessions run on sandbox compute that the provider operates and bills, not on the server you installed, so that compute arrives on the provider's invoice.
The self-hosted runtime guide covers the stack, agent runtime architecture explains what the runtime does, and the runtime comparison puts the hosting options side by side. Read the docs for how a session starts and stops.
Runtime cost questions
What is the runtime cost of AgentCore?
AgentCore bills per second of actual CPU and memory, with a one-second minimum. A Runtime session spans microVM ready, initialization, active processing and idle periods until it terminates; idle memory is reclaimed after 120 seconds in Runtime v2, and sessions last "up to 8 hours for each lifecycle on microVMs, or up to 14 days on Instances".
Can I avoid the credits meter by self-hosting?
Yes. Self-host is free, so the instance costs no credits. The session machine still runs on sandbox compute the provider operates and bills, so that line of the bill moves from Kortix to the provider instead of disappearing.
Pay for the credits your agents spend.
Read the pricing page, pick a tier, and stop the computer when the work is done.
Open source · Self-host is free · One isolated sandbox per session