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Vellum vs Patronus AI
Vellum and Patronus AI are tools for teams building AI products: Patronus AI builds training data and simulated environments that AI labs use to test and train agents, and Vellum versions prompts and workflows and tests them before they go live. Our editors read both companies' own sites, then read what AI engineers say about the two tools in public reviews, community boards and chat forums. The table below compares price, limits and features.
| What buyers compare | Vellum | Patronus AI |
|---|---|---|
| Price per monthSources 3, 4 | Assistant plans: Mighty $30, Super $100, Ultra $200, plus usage credits ($1 per credit). Workflow and evaluation platform pricing is not on the pricing page | Quote |
| Free plan or trialSources 3, 4 | Free start, with the first tasks included Free plan | Not published |
| How usage is countedSources 3, 4 | Credits pay for AI responses, web searches and image generation. Plans set the computer size and storage | Scoped per project |
| Integrations and featuresSources 3, 4 | Assistant email and subdomain on Super and Ultra | Training data, tasks and simulated environments for reinforcement learning |
| Security and deploymentSources 3, 4 | The Vellum assistant is open source and can be self-hosted with no platform fee | Not published |
| Best forSources 1, 2 | Product and ML teams that want versioned prompts and workflows, test suites and a check before changes go live, all in one workspace | AI labs that buy reinforcement learning tasks, graders and simulated software environments to train agents on long, multistep work |
List prices in US dollars per month before tax, as published on each vendor's site on October 16, 2026, billed monthly unless the cell says otherwise. "Quote" means the vendor sets the price through its sales team. A green check marks a row where the published data shows a clear edge.
Which one fits
The two solve different problems, so start with whether you are training agents or shipping an AI product.
Choose Vellum if
- You want prompts, workflows and test suites versioned in one workspace, with a check before a change goes live.
- You want something you can run yourself. The Vellum assistant is open source and has no platform fee when self-hosted.
- You are a product team that needs a visual workflow builder, along with code.
Choose Patronus AI if
- You are an AI lab or a platform team that needs simulated environments to test or train agents on long, multistep tasks.
- You want a vendor to build the training data and tasks for you. Patronus scopes and prices each project with the customer.
- You are testing agents before release more than you are monitoring a live app.
What buyers say
“Patronus is better when automated evaluation and safety scoring is the job. Vellum is better when prompt collaboration and A/B testing is the daily workflow.”
fakewrld_999 · r/LocalLLaMA · · source
“Vellum for the prompt IDE. Patronus for the judge layer, don’t pretend they’re interchangeable.”
No-Brick9938 · r/AIQuality · · source
“Vellum keeps our prompts, workflows, and test suites versioned in one place, with a check before a change goes live. Patronus is for labs that want simulated environments built for them, and each project is scoped and priced separately.”
Product engineer, Series A AI app company
Representative buyer view
Verdict
Vellum (7.0 out of 10, Conditional recommend) fits product teams shipping an AI app that want prompts, workflows and tests versioned in one place, with a check before each change goes live. Patronus AI (6.7 out of 10, Conditional recommend) fits AI labs and platform teams that want a vendor to build the training data and simulated environments they use to test agents before release.
Methodology
We read the Vellum and Patronus AI pricing pages and product sites on October 16, 2026 and recorded every published price, limit and plan feature. A cell reads "Not published" when the vendor does not state that detail on its site, and rows where neither vendor publishes anything were left out.
Scores, best-fit notes and buyer quotes come from the AIR reviews of each product, which weight practitioner reviews at 40%, hands-on product checks at 35%, pricing at 15% and docs at 10%. Paid reviews and pay-for-play sites are excluded. Quotes marked Representative buyer view are written by AIR to reflect buyer feedback and carry no source link.