Show HN: Mastra 1.0, open-source JavaScript agent framework from the Gatsby devs

Hi HN, we're Sam, Shane, and Abhi.

Almost a year ago, we first shared Mastra here (https://news.ycombinator.com/item?id=43103073). It’s kind of fun looking back since we were only a few months into building at the time. The HN community gave a lot of enthusiasm and some helpful feedback.

Today, we released Mastra 1.0 in stable, so we wanted to come back and talk about what’s changed.

If you’re new to Mastra, it's an open-source TypeScript agent framework that also lets you create multi-agent workflows, run evals, inspect in a local studio, and emit observability.

Since our last post, Mastra has grown to over 300k weekly npm downloads and 19.4k GitHub stars. It’s now Apache 2.0 licensed and runs in prod at companies like Replit, PayPal, and Sanity.

Agent development is changing quickly, so we’ve added a lot since February:

- Native model routing: You can access 600+ models from 40+ providers by specifying a model string (e.g., `openai/gpt-5.2-codex`) with TS autocomplete and fallbacks.

- Guardrails: Low-latency input and output processors for prompt injection detection, PII redaction, and content moderation. The tricky thing here was the low-latency part.

- Scorers: An async eval primitive for grading agent outputs. Users were asking how they should do evals. We wanted to make it easy to attach to Mastra agents, runnable in Mastra studio, and save results in Mastra storage.

- Plus a few other features like AI tracing (per-call costing for Langfuse, Braintrust, etc), memory processors, a `.network()` method that turns any agent into a routing agent, and server adapters to integrate Mastra within an existing Express/Hono server.

(That last one took a bit of time, we went down the ESM/CJS bundling rabbithole, ran into lots of monorepo issues, and ultimately opted for a more explicit approach.)

Anyway, we'd love for you to try Mastra out and let us know what you think. You can get started with `npm create mastra@latest`.

We'll be around and happy to answer any questions!

> That last one took a bit of time, we went down the ESM/CJS bundling rabbithole, ran into lots of monorepo issues, and ultimately opted for a more explicit approach.

shudders in vietnam war flashbacks congrats on launch guys!!!

for those who want an independent third party endorsement, here's Brex CTO talking about Mastra in their AI engineering stack http://latent.space/p/brex

LOL thanks swyx. Yeah we realized although we _could_ fight that war again...it would be better for everyone if we didn't...

And I actually hadn't seen that Brex piece so thanks for sharing!!

I've been building with Mastra for a couple of weeks now and loving it, so congratulations on reaching 1.0!

It's built on top of Vercel AI elements/SDK and it seems to me that was a good decision.

My mental heuristic is:

Vercel AI SDK = library, low level

Mastra = framework

Then Vercel AI Elements gives you an optional pre built UI.

However, I read the blog post for the upcoming AI SDK 6.0 release last week, and it seems like it's shifting more towards being a framework as well. What are your thoughts on this? Are these two tools going to align further in the future?

https://vercel.com/blog/ai-sdk-6

Never ask a woman her age, a man his salary, and an agent framework developer his long term plans

If it uses Vercel, I'm out.

Congratulations! I’m a fan of the publicity work and general out-of-the-box DX! That stuff matters a lot and I’m happy you’re aware.

I wonder: Are there any large general purpose agent harnesses developed using Mastra? From what I can tell OpenCode chose not to use it.

A lot of people on here repeat that rolling your own is more powerful than using Langchain or other frameworks and I wonder how Mastra relates to this sentiment.

When Langchain was the only option rolling your own made a lot of sense!

These days we see things going the other way, where teams that started rolling their own shift over to Mastra so they can focus on the agent vs having to maintain an internal framework.

The Latent Space article swyx linked earlier includes a quote from the Brex CTO talking about how they did that.

We use typescript for all our entire stack and it's super dope to see a production-grade framework (with no vendor lock in) launch!

Thanks! That's a lot of why we built Mastra. We wanted something that felt like it was made for us.

Congrats on the launch ! Someone told me that you have an excellent product but I don't have a need for it yet.

Thanks! And of course hope you try Mastra out when you do.

Why should I use this over say Strands Agents [1] or Spring AI [2]?

[1]: https://strandsagents.com

[2]: https://spring.io/projects/spring-ai

You should use whatever framework you feel like has the best DX / fits your stack best!

We're TypeScript-first, TypeScript-only so a lot of the teams who use us are full-stack TypeScript devs and want an agent framework that feels TS-native, easy to use, and feature-complete.

seems non of these are typescript-based? Strand appears to have a typescript sdk available but not natively ts.

Language, although an important factor, should not be the only factor to decide using a tool. I'm curious is there something unique Mastra is bringing to the table, compared to other alternatives.

Been using Mastra for some side projects for months and it's just phenomenal. Congrats to the team!

Thanks, great to hear!

> a `.network()` method that turns any agent into a routing agent

say more pls?

We've always supported letting folks specify their agent hierarchy, eg agent supervisor, workflow orchestrator, mix and match, etc.

But people kept asking us for a multi-agent primitive out of the box so we shipped `agent.network()`, which is basically dynamic hierarchy decided at runtime, pass in an array of workflows and agents to the routing agent and let it decide what to do, how long to execute for, etc!

https://mastra.ai/docs/agents/networks

ty! btw your docs search is broken, as i tweeted to Ward.

From punch cards to assembly, to C, to modern languages and web frameworks, each generation raised the abstraction. Agentic frameworks are the next one.

I mean we're framework guys so I would agree!

Congratulations on the launch. The landing page looks dope.

Thank you! We have an incredible designer and we love obsessing about this stuff.

So the ultimate real life use case of this is having a bubble on your site that you click to chat with a bot?! Most users prefer to chat with an actual human being 99% of the times or immediately ask the bot to chat with one.

Less frequently sites and more frequently a SaaS app, for example Sanity released a content agent in their CMS, Factorial released an agent inside their HR/payroll product.

But tons of other use cases too, eg dev teams at Workday and PayPal have built an agentic SRE to triage their alerts, etc etc

You’re not locked into a model, but you likely are locked in to a platform. This DX and convenience just shifts within the stack where the lock in occurs. Not criticizing - just a choice people should be conscious of.

Another useful question to ask: since you’re likely using 1 of 3 frontier models anyway, do you believe Claude Agent SDK will increasingly become the workflow and runtime of agentic work? Or if not Claude itself, will that set the pattern for how the work is executed? If you do, why use a wrapper?

Re: lessons from coding agents, we're building some of the key abstractions like sandboxes, filesystem, skills/knowledge as Mastra primitives in over the next month.

For any agent you're shipped to production though you probably want a harness that's open-source so you more fully control / can customize the experience.

I think that’s fair, totally, but I also think a Skill would be considered a primitive in and of itself by Anthropic. So to me it’s still wrapping an open primitive. Anyway, trade offs.

Offtopic but how much is AI used these days for generating code at your place? Curious because we see a major shift last months where almost everything is generated. Still human checked and human quality gates. Big difference compared to last year.

There's the normal stuff you'd expect -- we're all Opus-pilled, use Claude Code, a PR review bot etc. But it's been especially helpful with highly templatized code like our storage adapters, we already have 10-15 working examples which makes the n+1st adapter almost trivial to write.