Key findings
- Agents in real work draw the most praise, in 15 sources, then the TypeScript developer experience in 14 and the bundled workflows, memory, and evals in 8.
- Memory, recovery, and loop defects lead the concerns at 17 sources, followed by opinionated patterns at 8 and upgrades, dependencies, and the supply chain at 7.
- Builds, bundles, and hosting surprises appear in 7 sources, among them a Vercel function over 250 MB and a build that ran out of memory after an upgrade.
- License, lock-in, and vendor trust draw 5 current sources; two launch-era comments on the old license and missing prices are kept as history.
- Of 23 sources that describe keeping or leaving Mastra, 18 kept it and 5 moved to other code.
The public accounts behind Mastra's Signals agree on its TypeScript developer experience and split on whether teams keep it. The English-language sources span February 2025 to October 2026, from a Brex CTO interview and engineering posts by Sanity, Vasco, Brainforge, and Convex to a Postiz commit, Reddit threads, GitHub issues and solo developers.
What builders keep it for
Builders name the TypeScript experience and the parts that come in the box. A solo developer running a planning agent with 11 tools credits storage adapters for removing glue code, and a developer who shipped apps on both calls the AI SDK the model layer and Mastra the infrastructure layer.
Companies run it. Brex's CTO reports that about half of the company's agent-layer applications run on Mastra, Sanity uses it for its Content Agent, Brainforge kept its Mastra agents through a tracing migration, and Postiz ships Mastra memory and MCP packages in its product. Builders on r/LangChain and r/AI_Agents chose it over LangChain and LangGraph for TypeScript work.
Where it adds work
GitHub issues carry specific defects: Observational Memory adding 2 to 4 seconds per step, a turn blocked about 4 minutes when the observer failed, Anthropic tool IDs leaking into OpenAI requests, and durable runs that crash on recovery. Postiz measured its Mastra MCP server growing about 330 MB an hour in session mode.
Defaults draw the rest. Agents stop at the fifth step without an error, stacked retries turned one failing upstream into 18 requests, and an on-call agent's rollback fired twice after a restart.
Builds, dependencies, and the supply chain
Bundles and builds break on upgrades: a Cloudflare Workers bundle grew from about 541 KiB to about 22,469 KiB, and a build needed about 13 times more memory after @mastra/deployer 1.79.0. During the June 2026 npm compromise, one team's dependency bot pulled the malicious versions within minutes.
Why some teams moved on
Five sources moved away: Vasco to the Claude Agent SDK for better answers, a banking voice app to Pipecat, two projects to the AI SDK alone, and one team to a LangGraph rebuild. Ask these questions before you choose.
- Does the work need Mastra's workflows, memory, and evals, or only model calls and a chat UI?
- Which tools have side effects, and are they safe to run twice?
- Who pins and reviews @mastra upgrades?
- Will you count events per run before choosing a Mastra Platform plan?
Methodology
GILD synthesis of the 72 English-language public accounts in Mastra's Signals, opened on October 28, 2026 and published between February 2025 and October 2026. They comprise 21 Hacker News comments, 6 Reddit comments, 25 GitHub issues, 2 pull requests and 1 commit, 10 dev.to posts, 4 company engineering blogs, 1 personal blog, 1 podcast write-up, and 1 YouTube video. Reddit comments come from the Arctic Shift archive. Mastra's own blog and customer stories are left out of the counts, since they sit on the vendor's domain. Counts describe the sources reviewed and say nothing about Mastra users at large. Product behavior is checked against Mastra's documentation on the same date.
Products in this piece
Sources
- Public source
- 22
- Official documentation
- 4
- Latent Space: Full Story of Brex's AI Hail Mary, with Brex CTO James Reggio (Jan 17, 2026)
- Sanity Engineering: How we built our company agent harness (Oct 20, 2026)
- Sebastien Castiel (Vasco Engineering): Four Agent Frameworks in Sixteen Months (Jul 24, 2026)
- Uttam Kumaran (Brainforge): How we migrated to Langfuse v4 ahead of the cutover (Sep 18, 2026)
- Ian Macartney (Convex Stack): Reimplementing Mastra Workflows, Lessons Learned (Mar 28, 2025)
- Prakhar: Why I Love Mastra, Building Production AI Agents That Actually Work (Jan 3, 2026)
- Kristian: Mastra vs AI SDK, I built production apps with both (YouTube, Jun 17, 2026)
- DevOps Daily on dev.to: We Built an On-Call Agent in Mastra, Where It Won and Where It Would Not (Aug 12, 2026)
- Aman Kumar on dev.to: Using Mastra agents with a custom OpenAI-compatible API, the silent 5-step limit (Oct 18, 2026)
- owen adira on dev.to: Building a portfolio agent that can't make things up (Sep 30, 2026)
- Mastra issue #15677: Observational Memory adds 2 to 4 seconds per agent step (Apr 23, 2026)
- Mastra issue #21849: an Observational Memory observer failure blocks a turn for about 4 minutes (Aug 19, 2026)
- Mastra issue #15729: Anthropic tool IDs leak into OpenAI requests (Apr 24, 2026)
- Mastra issue #22636: EventedAgent recover() crashes after a process restart (Aug 30, 2026)
- Mastra issue #3309: bundle size regression blocks Cloudflare Workers deployments (Mar 28, 2025)
- Mastra issue #7348: Vercel function exceeds the 250 MB unzipped limit (Sep 3, 2025)
- Mastra issue #28645: mastra build needs about 13 times more memory since @mastra/deployer 1.79.0 (Oct 27, 2026)
- Mastra issue #18048: @mastra/core 1.42.1 and related versions publish a malicious typosquat (Jun 17, 2026)
- paulclarke.au pull request 49: research agents moved to the AI SDK, Mastra removed (Oct 16, 2026)
- Hacker News comment on Mastra's opinionated patterns and a LangGraph rebuild (Jan 21, 2026)
- Hacker News comment on clunky rule-based branching in Mastra workflows (Jan 21, 2026)
- Hacker News comment on swapping Mastra for Pipecat in a banking voice app (Apr 27, 2026)
- Mastra docs: Memory overview
- Mastra reference: Agent.generate() (maxSteps default 5)
- Mastra docs: Workflows overview
- Mastra docs: Deployment overview (Node.js 22.13, Hono server, deployers)