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Quick answer
HolmesGPT is an open source investigation agent and K8sGPT an open source Kubernetes scanner. Both are CNCF sandbox projects, free, and run by you with your own model. RubixKube is an AI SRE that runs for you: always-on observers, triage and grouping, an RCA with checked evidence for every incident, memory of past fixes, and changes you approve.
Pick the open source tools if you want to run and tune everything yourself. Pick RubixKube if you want it working on your incidents today, without building the rest.
What is HolmesGPT?
HolmesGPT is a free, open source investigation agent and a CNCF sandbox project. You run it yourself, as a CLI, Helm chart or server, with your own model, and connect it to Kubernetes, clouds and observability tools. It is read-only by design.
- How you get it: free and self-hosted. Slack and Teams come through Robusta's commercial product.
- Best for: teams that want open source and will run and tune it. See RubixKube vs HolmesGPT and K8sGPT.
What is K8sGPT?
K8sGPT is a free, open source CLI and CNCF sandbox project that scans Kubernetes clusters with built-in analyzers and explains problems in plain English, using the AI model you choose.
- How you get it: free and self-hosted, as a CLI, an operator or an MCP server.
- Best for: a free first look at one Kubernetes cluster.
What is RubixKube?
RubixKube runs read-only observers in your Kubernetes clusters, AWS, Google Cloud and Azure accounts and Linux machines, and takes alerts from Datadog, PagerDuty, Grafana, Sentry and other tools by webhook. It groups related alerts into one incident, and its agent, Rubix, writes a root cause analysis for each one, citing the tool output behind every step. Quotes are checked in code against what the tools returned, so you can see exactly what Rubix read.
Every RCA proposes a Fix and Follow-ups. Rubix opens the change as a pull request or through any tool you connect, and you choose how much it may do: Observe only reads, Assist asks before every change, Auto asks before anything destructive. It remembers past incidents and fixes, and works in the console, Slack, the CLI and your own AI tools over MCP.
- How you get it: sign up and start today. No demo, no approval.
- Pricing: Individual is free (1 environment, 10 investigations a month). Business is $999 a month. Enterprise is custom. See pricing.
- Best for: teams that run on more than one platform and want an AI SRE they can try on their own systems this afternoon.
How they differ
K8sGPT vs HolmesGPT vs RubixKube
| K8sGPT | HolmesGPT | RubixKube | |
|---|---|---|---|
| What it is | Open source Kubernetes scanner | Open source investigation agent | AI SRE platform |
| Where it works | Kubernetes | Kubernetes, clouds and tools you connect | Kubernetes, AWS, Google Cloud, Azure, Linux machines, alerting tools |
| Runs on its own | When you scan, or as an operator | When you ask, or on schedules you set | Every incident, automatically |
| Alert grouping | No | No | Yes, one RCA per group |
| Evidence | Analyzer output | Tool output | Every claim cited, quotes checked in code |
| Memory of past incidents | No | No | Yes, incidents, RCAs, fixes and ratings |
| Changes | Auto-remediation when you enable it | Read-only | Observe, Assist or Auto |
| You run it | Yes | Yes | No, it runs for you |
| Price | Free, plus your model | Free, plus your model | Free plan, Business $999 a month |
What you would build around the open source tools
The open source tools are good at one step: looking at a problem when you point them at it. To get what an AI SRE does for a team, you would also need:
- Observers that watch every cluster, cloud and machine, all the time
- Triage and grouping, so an alert storm becomes one incident
- Evidence checks, so an answer cites what the tools really returned
- Memory of past incidents, RCAs and what fixed them
- Approvals, audit and modes before anything touches production
- Slack, a console and a CLI for the whole team
RubixKube is all of that, already running.
When open source is the right choice
- You want full control and will run, host and tune the tool yourself
- You need everything inside your own network
When RubixKube is the right choice
- You want every incident investigated without anyone asking
- Your stack is more than Kubernetes
- You want the team, not one engineer, to use it
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Frequently asked questions
Is RubixKube open source?
No. RubixKube is a hosted AI SRE with a free plan. Its CLI is free on npm, and it works with your own AI tools over MCP.
Is K8sGPT or HolmesGPT better?
They do different jobs. K8sGPT scans a Kubernetes cluster and explains problems. HolmesGPT investigates an alert or question across Kubernetes and connected tools. Neither watches all the time or groups alerts on its own.
Can I use RubixKube for free?
Yes. The Individual plan is free, with 1 environment and 10 investigations a month.