Tool profile
Opik (Comet): cost, fit and limits
Opik is an open-source LLM evaluation and observability platform made by Comet ML, Inc. in New York that includes a versioned prompt library, tracing, test suites and an agent playground. It runs as free self-hosted software or as Comet's hosted cloud, and developers use Python and TypeScript SDKs.
What to know first
Opik is the cheapest paid route in this ranking: Pro Cloud is $19 a month for up to 50 members and 100k spans, and the open-source version is free. Prompts are versioned automatically and fetched by name, version or environment. The prompt docs show Python and TypeScript only. Cloud retention is 60 days on both free and Pro unless customized, and SSO is an Enterprise item.
Opik (Comet) at a glance
| Maker | Comet ML, Inc., United States |
|---|---|
| Free plan | Yes |
| Entry price | $19 per month (Pro Cloud) |
| API access | Yes |
| Category | Best AI Prompt Management Software in 2026, rank 3 of 10 |
| Website | comet.com/site/products/opik/ |
Who Opik (Comet) is best for
Small teams with a tight budget
Free Cloud allows 10 members and 25k spans, and Pro Cloud costs $19 monthly, so prompt history and tracing are available before any real revenue exists.
Python and TypeScript developers
The prompt docs show create and get calls in both languages, including chat prompts with system, user and assistant messages, so a registry call fits into existing application code.
Teams that want to tune prompts automatically
The product page lists a Prompt Optimizer with six optimization algorithms and an Agent Playground that tracks and versions prompt and parameter sets.
Buyers wanting a self-hosted fallback
The pricing page says the open-source version uses the same codebase as the hosted versions, so moving between self-managed and cloud does not change the product.
Opik (Comet) plans and pricing
| Plan | Price | What it includes |
|---|---|---|
| Open Source | $0 | Self-host from GitHub with the same codebase as the hosted versions. Includes tracing, test suites and the Agent Playground. |
| Free Cloud | $0 | Up to 10 team members, 25k spans a month and 60-day data retention. Includes a trial of the Ollie coding harness. |
| Pro Cloud | $19 per month | Up to 50 team members and 100k spans a month, 60-day retention. Extra spans cost $5 per 100k, and 400-day retention costs $29 per 100k spans. |
| Enterprise | Custom | Unlimited team members, custom usage plans, flexible deployments, SSO, service accounts, view-only users, SLA support, and SOC 2, ISO 27001, HIPAA and GDPR compliance. |
Checked October 2026.
What Opik (Comet) does
- Automatic prompt versions
- Each change to a prompt creates a new version. A fetch can omit the version to get the latest, name a version such as v3, or request the one deployed to an environment like production.
- Variables and chat prompts
- Placeholders such as a domain variable are filled at runtime with a format call. Multi-turn chat prompts keep system, user and assistant messages together under one prompt name.
- Trace linking
- Calling the prompt-fetch function inside a tracked function attaches that exact prompt version to the trace, which answers which wording produced a given output. This works in Python and TypeScript.
- Prompt Optimizer
- The product page names six prompt optimization algorithms for tuning prompts across an agent. Results are meant to be saved as a new version in the library.
- Agent Playground
- Sets of prompts and parameters are tracked and versioned, and successful versions can be deployed from the playground, which is described in the product page.
How Opik (Comet) handles your data
Opik's pricing page lists SOC 2, ISO 27001, HIPAA and GDPR compliance for Enterprise, and 60-day data retention on Free Cloud and Pro Cloud, with a 400-day extension priced per span. The about page says Comet is based in New York with an office in Tel Aviv and links its security badges to trust.comet.com, which was not opened for this page. The open-source version can be self-hosted, which keeps prompts in your own infrastructure. Comet's privacy policy and any statement on training with customer data were not checked for this page.
Where Opik (Comet) falls short in practice
- SDK coverage in the prompt docs. The prompt management guide shows Python and TypeScript only. A Java, Go or Ruby service would need the REST API, and the page read does not document it.
- Retention caps on cloud plans. Both Free Cloud and Pro Cloud keep data 60 days unless customized, and the longer 400-day option is billed per 100k spans, so long-term version comparisons add cost.
- Prompt library is a smaller surface. The product page describes prompts through the Agent Playground and does not describe a standalone library page, so editors who want a content-style interface should trial it first.
- SSO needs a contract. Single sign-on, service accounts and view-only users are Enterprise features, which makes the $19 plan unsuitable for companies with an identity-provider rule. Enterprise pricing is not published on the pages read.
Works with
Alternatives to Opik (Comet)
Opik (Comet): common questions
How does Opik link a prompt version to a trace?
If you call the prompt-fetch function inside a function tracked with the track decorator in Python or the track wrapper in TypeScript, Opik links the exact prompt version used to that trace. This lets you filter traces by the wording that produced them.
Is Opik really free to use?
The pricing page says the full Opik feature set is free for as long as you like, through open-source self-hosting or Free Cloud with 10 members and 25k spans. Paid items are Pro Cloud at $19 monthly, extra spans at $5 per 100k, and the Ollie assistant after its trial.
Can Opik prompts target an environment?
Yes. The docs say a fetch can omit the version for the newest, name a version, or use an environment such as production for the version deployed there. Environments are chosen in the Opik UI, so moving production forward is a console action.
What does Opik Pro Cloud include at $19?
Pro Cloud lists up to 50 team members, 100k spans a month and 60-day retention, with span limits and retention customizable. Extra spans cost $5 per 100k and 400-day retention costs $29 per 100k spans. SSO and service accounts are not part of it.
Where is Opik's maker based?
The Comet about page says the company is based in New York City with an office in Tel Aviv, and describes a remote-first workforce. It lists 80 employees in 14 countries. Hosting regions for Opik Cloud were not stated on the pages read, so ask before storing regulated content.