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 Vercel AI SDK: Which is Better in 2026?

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Agent Framework

Choosing between Letta and Vercel AI SDK? 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.

Vercel AI SDK is for: TypeScript and React teams adding streaming chat, tool calling and structured output to a web app, with any model provider.

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 Vercel AI SDK if you’re building AI features into a React or Next.js app.

Letta vs Vercel AI SDK — Side by Side

	Letta	Vercel AI SDK
Category	Agent Framework	Agent Framework
What it is	Agent server and SDKs: agents with persistent memory	Code library: TypeScript toolkit for AI apps and agents
Languages	Python and TypeScript SDKs	TypeScript/JavaScript
Licence	Apache 2.0	Apache 2.0
Managed / paid option	Letta API: free tier, Pro $20/month plus usage	None; deploy anywhere
Project status	Active	Active; v6
Pricing	Free · paid from $20/mo	Free
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 — React and Next.js apps, streaming chat UI, provider switching

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

Vercel AI SDK

Best DX for TS/React AI apps
Provider-agnostic
Free and open-source
Great streaming & UI hooks

TypeScript/JS only
Less suited to complex Python agent graphs

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

Vercel AI SDK

One API across OpenAI, Anthropic, Google and other providers
Streaming, tool calling and structured output
UI hooks for chat interfaces in React and other frameworks
AI SDK 6 adds an agent abstraction, tool approval steps, DevTools and MCP support
Runs on any host, not only Vercel
Apache 2.0 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 Vercel AI SDK if…

You’re building AI features into a React or Next.js app.
You want to switch model providers without rewriting calls.
You need streaming UI and tool calls more than complex multi-agent graphs.

Vercel AI SDK review & pricing

Frequently Asked Questions

Is Letta better than Vercel AI SDK?⌄

What is the difference between Letta and Vercel AI SDK?⌄

What it is — Letta: Agent server and SDKs: agents with persistent memory. Vercel AI SDK: Code library: TypeScript toolkit for AI apps and agents. Languages — Letta: Python and TypeScript SDKs. Vercel AI SDK: TypeScript/JavaScript. Managed / paid option — Letta: Letta API: free tier, Pro $20/month plus usage. Vercel AI SDK: None; deploy anywhere. Project status — Letta: Active. Vercel AI SDK: Active; v6.

Letta vs Vercel AI SDK: which is cheaper?⌄

Letta pricing: Free · paid from $20/mo. Vercel AI SDK pricing: Free. Confirm current pricing on each tool's official site, as plans change.

Which is rated higher, Letta or Vercel AI SDK?⌄

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

When should I skip both Letta and Vercel AI SDK?⌄

Skip Letta if you only need short-lived task agents. A lighter SDK is simpler. Skip Vercel AI SDK if your team writes Python. LangChain, CrewAI or the OpenAI Agents SDK fit better.

Sources · tool facts checked October 2026