[HN Gopher] Show HN: Mastra 1.0, open-source JavaScript agent fr...
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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!
Author : calcsam
Score : 51 points
Date : 2026-01-20 16:38 UTC (6 hours ago)
(HTM) web link (github.com)
(TXT) w3m dump (github.com)
| holoduke wrote:
| 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.
| calcsam wrote:
| 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.
| microflash wrote:
| 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
| pancomplex wrote:
| seems non of these are typescript-based? Strand appears to have
| a typescript sdk available but not natively ts.
| microflash wrote:
| 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.
| calcsam wrote:
| 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.
| pancomplex wrote:
| 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!
| calcsam wrote:
| Thanks! That's a lot of why we built Mastra. We wanted
| something that felt like it was made for us.
| bradledford wrote:
| Been using Mastra for some side projects for months and it's just
| phenomenal. Congrats to the team!
| calcsam wrote:
| Thanks, great to hear!
| simlevesque wrote:
| Congrats on the launch ! Someone told me that you have an
| excellent product but I don't have a need for it yet.
| calcsam wrote:
| Thanks! And of course hope you try Mastra out when you do.
| anditherobot wrote:
| From punch cards to assembly, to C, to modern languages and web
| frameworks, each generation raised the abstraction. Agentic
| frameworks are the next one.
| calcsam wrote:
| I mean we're framework guys so I would agree!
| mrcwinn wrote:
| 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?
| calcsam wrote:
| 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.
| mrcwinn wrote:
| 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.
| swyx wrote:
| > 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
| calcsam wrote:
| LOL thanks swyx. Yeah we realized although we _could_ fight
| that war again...it would be better for everyone if we
| didn't...
| calcsam wrote:
| And I actually hadn't seen that Brex piece so thanks for
| sharing!!
| solarkraft wrote:
| 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.
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