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

github.com

74 points by calcsam 8 hours ago

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!

swyx - 4 hours ago

> 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

esperent - an hour ago

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

solarkraft - 2 hours ago

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.

pancomplex - 5 hours ago

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!

simlevesque - 4 hours ago

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

microflash - 5 hours ago

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

bradledford - 5 hours ago

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

swyx - 2 hours ago

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

say more pls?

anditherobot - 4 hours ago

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

admiralrohan - an hour ago

Congratulations on the launch. The landing page looks dope.

tamimio - 2 hours ago

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.

mrcwinn - 4 hours ago

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?

holoduke - 5 hours ago

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.