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 LlamaIndex: Which is Better in 2026?

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Agent Framework

Choosing between Letta and LlamaIndex? 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.

LlamaIndex is for: Teams whose agents mostly work over their own documents and data, and who want parsing, indexing and retrieval handled well.

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 LlamaIndex if your agents mainly answer questions over PDFs, docs or other internal data.

Letta vs LlamaIndex — Side by Side

	Letta	LlamaIndex
Category	Agent Framework	Agent Framework
What it is	Agent server and SDKs: agents with persistent memory	Code library: data and RAG framework with agents
Languages	Python and TypeScript SDKs	Python, TypeScript
Licence	Apache 2.0	MIT
Managed / paid option	Letta API: free tier, Pro $20/month plus usage	LlamaCloud: Free, Starter $50, Pro $500 (credit-based)
Project status	Active	Active
Pricing	Free · paid from $20/mo	Free · then usage-based
Starting price	Free tier available	Free tier available
Free tier
Rating	4.0	4.5
Best for	Agent Framework — long-term memory, stateful agents, self-host or hosted	Agent Framework — RAG over documents, document parsing, data connectors

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

LlamaIndex

Excellent RAG tooling
Strong document parsing (LlamaParse)
Open-source
Many data connectors

Overlaps with LangChain (choose one)
Cloud features usage-priced

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

LlamaIndex

Data connectors, indexing and retrieval for RAG
Agent workflows on top of your indexed data
LlamaParse document parsing, billed in credits by page and tier
LlamaCloud plans: Free (10K credits), Starter ($50), Pro ($500); credits at $1.25 per 1,000
Python and TypeScript libraries
MIT 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 LlamaIndex if…

Your agents mainly answer questions over PDFs, docs or other internal data.
You need reliable parsing of complex documents such as tables and scanned pages.
You want a managed parsing and indexing service you can add later.

LlamaIndex review & pricing

Frequently Asked Questions

Is Letta better than LlamaIndex?⌄

What is the difference between Letta and LlamaIndex?⌄

What it is — Letta: Agent server and SDKs: agents with persistent memory. LlamaIndex: Code library: data and RAG framework with agents. Languages — Letta: Python and TypeScript SDKs. LlamaIndex: Python, TypeScript. Licence — Letta: Apache 2.0. LlamaIndex: MIT. Managed / paid option — Letta: Letta API: free tier, Pro $20/month plus usage. LlamaIndex: LlamaCloud: Free, Starter $50, Pro $500 (credit-based).

Letta vs LlamaIndex: which is cheaper?⌄

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

Which is rated higher, Letta or LlamaIndex?⌄

In our catalog, Letta rates 4.0 out of 5 and LlamaIndex rates 4.5 out of 5, so LlamaIndex has a slight edge on reviews.

When should I skip both Letta and LlamaIndex?⌄

Skip Letta if you only need short-lived task agents. A lighter SDK is simpler. Skip LlamaIndex if your agent mostly calls tools and APIs rather than reading documents. LangGraph or the OpenAI Agents SDK fit better.

Sources · tool facts checked October 2026