What is App Stack Builder?

App Stack Builder is a free AI-powered tool that helps founders and developers choose the right tech stack for their projects based on budget, app type, team size, and skill level.

What is the best tech stack for SaaS in 2026?

The best tech stack for SaaS in 2026 typically includes Next.js 16 for frontend, Supabase for database and auth, Vercel for hosting, Stripe for payments, and PostHog for analytics. App Stack Builder can generate a personalized recommendation based on your specific budget and requirements.

Is App Stack Builder free to use?

Yes, App Stack Builder is completely free to use. You can generate unlimited tech stack recommendations without any cost.

What types of apps can I build with the recommended stacks?

App Stack Builder supports various app types including SaaS applications, web apps, mobile apps, e-commerce stores, internal tools, and AI/ML products.

How much does a SaaS tech stack cost per month?

A modern SaaS tech stack can cost anywhere from $0-50/month for bootstrapped startups using free tiers, $100-300/month for growth-stage startups, to $500+/month for enterprise-ready infrastructure. App Stack Builder helps you find the best tools within your specific budget.

What is the best tech stack for solo founders?

For solo founders, we recommend Next.js + Vercel (free), Supabase (free tier), Supabase Auth (free), Stripe (pay as you go), and Plausible or PostHog for analytics. This stack can run your entire SaaS for under $50/month.

Can I export my tech stack recommendations?

Yes, you can export your tech stack recommendations as a PDF document or copy them to your clipboard. You can also share a link to your stack with others.

Letta vs Mastra: Which is Better in 2026?

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Agent Framework

Choosing between Letta and Mastra? Both are popular agent framework tools. Below we compare them on pricing, free tiers, features, and pros & cons so you can pick the right fit for your stack.

Letta is for: Teams building agents that must remember users and context across sessions and restarts, with memory as the core design.

Mastra is for: TypeScript teams that want agents, workflows, memory, evals and observability in one framework instead of assembling them.

Quick verdict

There’s no single winner; pick on your constraint. Choose Letta if your agent must remember users and past sessions over weeks or months. Choose Mastra if you work in TypeScript and want workflows, memory and evals included.

Letta vs Mastra — Side by Side

	Letta	Mastra
Category	Agent Framework	Agent Framework
What it is	Agent server and SDKs: agents with persistent memory	Code library: TypeScript agent framework with workflows
Languages	Python and TypeScript SDKs	TypeScript
Licence	Apache 2.0	Apache 2.0 core; enterprise features under a separate licence
Managed / paid option	Letta API: free tier, Pro $20/month plus usage	Mastra Cloud: free Starter, Teams $250/month
Project status	Active	Active; 1.x
Pricing	Free · paid from $20/mo	Free · then usage-based
Starting price	Free tier available	Free tier available
Free tier
Rating	4.0	4.6
Best for	Agent Framework — long-term memory, stateful agents, self-host or hosted	Agent Framework — TypeScript agents, workflows and memory, batteries included

Pros & Cons

Letta

Memory is the design centre, not an add-on
Agents survive restarts with state intact
Comes from the MemGPT paper

Younger project with a moving API
Memory model is opinionated

Mastra

Best-in-class for TypeScript teams
Batteries-included (agents, workflows, memory, evals)
From the experienced Gatsby team
Strong observability & MCP support

Younger than Python frameworks
TypeScript-only ecosystem

Key Features Compared

Letta

Persistent, self-editing agent memory (from the MemGPT research)
Agents keep their state across restarts
Self-hosted server, or the hosted Letta API
Hosted plans: free tier and Pro at $20 a month with pay-as-you-go usage
Letta Code, an open-source coding agent with memory across sessions
Apache 2.0 licence

Mastra

Agents, a graph-based workflow engine and memory in one package
Built-in evals and observability
MCP support for sharing tools
Mastra Cloud: free Starter, Teams at $250 a month, Enterprise on quote
Apache 2.0 core; enterprise features under a separate Mastra Enterprise Licence

Choose Letta if…

Your agent must remember users and past sessions over weeks or months.
You want agents that keep state when the process restarts.
You want the choice of self-hosting or a hosted API.

Letta review & pricing

Choose Mastra if…

You work in TypeScript and want workflows, memory and evals included.
You want an optional managed cloud from the same team.
You want MCP tool sharing built in.

Mastra review & pricing

Frequently Asked Questions

Is Letta better than Mastra?⌄

What is the difference between Letta and Mastra?⌄

What it is — Letta: Agent server and SDKs: agents with persistent memory. Mastra: Code library: TypeScript agent framework with workflows. Languages — Letta: Python and TypeScript SDKs. Mastra: TypeScript. Licence — Letta: Apache 2.0. Mastra: Apache 2.0 core; enterprise features under a separate licence. Managed / paid option — Letta: Letta API: free tier, Pro $20/month plus usage. Mastra: Mastra Cloud: free Starter, Teams $250/month. Project status — Letta: Active. Mastra: Active; 1.x.

Letta vs Mastra: which is cheaper?⌄

Letta pricing: Free · paid from $20/mo. Mastra pricing: Free · then usage-based. Confirm current pricing on each tool's official site, as plans change.

Which is rated higher, Letta or Mastra?⌄

In our catalog, Letta rates 4.0 out of 5 and Mastra rates 4.6 out of 5, so Mastra has a slight edge on reviews.

When should I skip both Letta and Mastra?⌄

Skip Letta if you only need short-lived task agents. A lighter SDK is simpler. Skip Mastra if your team writes Python. LangGraph or CrewAI fit better.

Sources · tool facts checked October 2026