Pydantic AI vs Mastra: license, pricing and features compared (October 2026)
Pydantic AI and Mastra are both listed under Agent building. Pydantic AI is open source (MIT); Mastra is not: not a single standard license on GitHub (read the repository's license files). GitHub stars on Oct 25, 2026: Mastra 29,073 (mastra-ai/mastra) vs Pydantic AI 20,868 (pydantic/pydantic-ai). Stars measure attention, not quality. Pydantic AI is the better fit for: Python teams that value type safety and validation. Mastra is the better fit for: TypeScript and Next.js teams building agents. Facts were read from vendor and GitHub pages on Oct 25, 2026 and are Reported; what we ran ourselves is under What we measured.
Our pick: Pick Pydantic AI for python teams that value type safety and validation; pick Mastra for typeScript and Next.js teams building agents. No overall winner: we have not benchmarked them against each other. Updated (America/Chicago).
Evidence: Both tools have a Tested entry (scope on each tool page). The facts in the tables were read from each vendor's own pages and the public GitHub API on 2026-10-25 (America/Chicago) and are Reported. The What we measured section lists what we have actually run, with links to the test logs, and what we have not run yet; anything we could not confirm is marked as not captured.
Pydantic
Tested (smoke test)
Python agent framework built on Pydantic types, covering agents, realtime voice, image generation and embeddings.
Mastra · @mastra/core@1.79.0
Tested (smoke test)
A strong TypeScript option if you are building agents in a Node stack; read the breaking-change note on sessions before upgrading.
Side by side, from what we recorded
Each row compares one recorded fact for both tools. Rows are not weighted and nothing is added up into a score; the note under each row says what the marker means.
Evidence
Tested (smoke test) for Pydantic AITested (smoke test) for MastraTested = we ran it (smoke test); Reported = we read official sources
Smoke-test result
Passed for Pydantic AIPassed for MastraEach tool's own smoke test on the same CPU-only machine; tasks differ unless the logs say otherwise
Release date
Oct 25, 2026 (Pydantic AI is ahead on this row) for Pydantic AIOct 21, 2026 for MastraNewer date only; says nothing about quality
Pricing we could verify
Verified from official page (Pydantic AI is ahead on this row) for Pydantic AINot verified for MastraAbout our evidence only, not about the price
Steps in our setup guide
2 for Pydantic AI3 for MastraCounts our guide's steps, not difficulty
Sources we cite
2 for Pydantic AI2 for MastraHow much we had to read; more is not better
A list of recorded differences, not a quality score or a ranking. We have not benchmarked these tools against each other; the smoke-test row links each tool's own log. How we label evidence.
What we measured
We ran both Pydantic AI and Mastra ourselves; the table links each full test log. These are smoke tests on one CPU-only machine, not benchmarks. Each tool had its own task, so the two results are not a head-to-head. Model-driven runs used a small local Qwen2.5-3B-Instruct model.
| Test | Pydantic AI | Mastra |
|---|---|---|
| Hands-on test log (install and a real task) | Tested: Pydantic AI 2.61.0, Oct 25, 2026: passed. Pydantic AI 2.61.0 passed our one-tool task on a local 3B model: 3 of 3 trials; cold uv install 3.7 s. Full test log | Tested: Mastra 0.24.9 (Node 20) / 1.79.0 (Node 24), Oct 25, 2026: passed. Mastra passed 5 of 5 on Node 20 (0.24.9) and 5 of 5 on Node 24 (1.79.0) with temperature pinned to 0, after failing 5 of 6 earlier trials at default sampling. Full test log |
How we test and label results: methodology. All test logs: test hub.
Get the weekly brief: which AI tools to update, try or skip. Free.
Free. Unsubscribe anytime. No spam. We email a confirmation link first. Privacy
Pydantic AI vs Mastra at a glance
Pydantic AI and Mastra are both listed under Agent building. Pydantic AI: Python agent framework built on Pydantic types, covering agents, realtime voice, image generation and embeddings. Mastra: A strong TypeScript option if you are building agents in a Node stack; read the breaking-change note on sessions before upgrading.
| Feature | Pydantic AI | Mastra |
|---|---|---|
| Vendor | Pydantic | Mastra |
| Listed under | Agent building | Agent building |
| License | MIT | Not a single standard license on GitHub (read the repository's license files) |
| Pricing model | Free and open source | Not captured on the pages we read |
| Free tier | Free to self-host | Not captured on the pages we read |
| Paid plans | None listed for the library | Not captured on the pages we read |
| Platforms | Python | Not captured on the pages we read |
| Public repository | pydantic/pydantic-ai: 20,868 stars, last push Oct 26, 2026 UTC (GitHub API, Oct 25, 2026) | mastra-ai/mastra: 29,073 stars, last push Oct 26, 2026 UTC (GitHub API, Oct 25, 2026) |
| Latest release we saw | Oct 25, 2026 | @mastra/core@1.79.0, Oct 21, 2026 |
| Evidence | Tested (scope on its tool page) | Tested (scope on its tool page) |
How Pydantic AI and Mastra differ
- Pydantic AI is open source (MIT); Mastra is not: not a single standard license on GitHub (read the repository's license files).
- GitHub stars on Oct 25, 2026: Mastra 29,073 (mastra-ai/mastra) vs Pydantic AI 20,868 (pydantic/pydantic-ai). Stars measure attention, not quality.
- Pydantic AI is "Free and open source"; the entry for Mastra has no pricing model we could confirm (pricing not verified).
- Latest release we saw: Pydantic AI's newest release on Oct 25, 2026; Mastra @mastra/core@1.79.0 on Oct 21, 2026 (4 days earlier).
- Pydantic AI's pricing details were captured; Mastra's were not published or could not be read, so a price comparison would be one-sided.
Which should you pick?
- Pick Pydantic AI if: Python teams that value type safety and validation. Skip it if: you need a TypeScript framework.
- Pick Mastra if: TypeScript and Next.js teams building agents; teams that need observability and tracing out of the box. Skip it if: you work in Python.
Strengths and limits
| Feature | Pydantic AI | Mastra |
|---|---|---|
| Strengths | Type-safe design; MIT license | TypeScript-native; Detailed release notes with highlights; Strong observability additions in this release |
| Limits | Python only; Our test was one small task on a local 3B model; it does not show behaviour with hosted models or larger jobs | Breaking change to agent controller sessions in this release; License reported as NOASSERTION on GitHub, so check the repository's license text; Some features are experimental |
What we did not verify
- Mastra: License terms (GitHub reports NOASSERTION).
- Output quality, speed and reliability beyond the smoke tests listed under What we measured: not compared.
FAQ
Is Pydantic AI or Mastra open source?
Pydantic AI: MIT. Mastra: Not a single standard license on GitHub (read the repository's license files). Licenses come from each project's GitHub repository or the vendor's own pages, read Oct 25, 2026; read the license text itself before redistributing or building a competing service.
Does Pydantic AI or Mastra have a free plan?
Pydantic AI: Free: to self-host. Mastra: we did not capture free-tier details. Checked Oct 25, 2026; prices and limits change, so confirm on each vendor's page.
Which was updated more recently, Pydantic AI or Mastra?
Pydantic AI's newest release we saw is (Oct 25, 2026); Mastra's is @mastra/core@1.79.0 (Oct 21, 2026). Read Oct 25, 2026 from the official release page or repository; a newer date is not a quality ranking.
What is the main difference between Pydantic AI and Mastra?
Pydantic AI is open source (MIT); Mastra is not: not a single standard license on GitHub (read the repository's license files). GitHub stars on Oct 25, 2026: Mastra 29,073 (mastra-ai/mastra) vs Pydantic AI 20,868 (pydantic/pydantic-ai). Stars measure attention, not quality.
Sources
- Pydantic AI docs (fetched 2026-10-25)
- Pydantic AI repository (GitHub) (fetched 2026-10-25)
- @mastra/core@1.79.0 release (fetched 2026-10-25)
- README (fetched 2026-10-25)
Related
Page history
- : First published. Facts read from vendor pages and the GitHub API on 2026-10-25.
Markdown version for agents: /compare/pydantic-ai-vs-mastra.md
Free · weekly · about six minutes
Get The Weekly Verdict, free
What shipped this week, what is worth switching to, and what to ignore. We run what we can and label what we only read.
- One email a week. Each release gets one call: update now, worth a look, or skip.
- Every claim shows its evidence. Reported means we read the sources; Tested means we ran it, with the exact scope and the failures left in.
- A free AI Tools Cheat Sheet (web page and printable PDF) lands in your inbox when you confirm.
Free. Unsubscribe anytime. No spam. We email a confirmation link first and add you only after you click it. We use your email only to send this newsletter and never sell it. Privacy