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.

DSPy vs Letta: Which is Better in 2026?

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Agent Framework

Choosing between DSPy and Letta? 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.

DSPy is for: Teams with an evaluation set who want to optimize prompts and LLM pipelines against a metric instead of hand-tuning them.

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

Quick verdict

There’s no single winner; pick on your constraint. Choose DSPy if you have examples and a metric, and want prompts tuned automatically. Choose Letta if your agent must remember users and past sessions over weeks or months.

DSPy vs Letta — Side by Side

	DSPy	Letta
Category	Agent Framework	Agent Framework
What it is	Code library: framework for optimizing prompts and LLM programs	Agent server and SDKs: agents with persistent memory
Languages	Python	Python and TypeScript SDKs
Licence	MIT	Apache 2.0
Managed / paid option	None	Letta API: free tier, Pro $20/month plus usage
Project status	Active; 3.x	Active
Pricing	Free	Free · paid from $20/mo
Starting price	Free tier available	Free tier available
Free tier
Rating	4.2	4.0
Best for	Agent Framework — prompt optimization, evaluation-driven, research-backed	Agent Framework — long-term memory, stateful agents, self-host or hosted

Pros & Cons

DSPy

Replaces prompt tinkering with measurable optimisation
Strong research backing (Stanford)
Composes well with any model provider

A genuinely different mental model to learn
Optimisation runs cost tokens

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

Key Features Compared

DSPy

Signatures and modules replace hand-written prompts
Optimizers, including GEPA, that tune prompts against your metric
Works with most model providers
From Stanford NLP
MIT licence

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

Choose DSPy if…

You have examples and a metric, and want prompts tuned automatically.
Your pipeline keeps breaking when you switch models, and you want to re-optimize instead of rewriting prompts.

DSPy review & pricing

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

Frequently Asked Questions

Is DSPy better than Letta?⌄

What is the difference between DSPy and Letta?⌄

What it is — DSPy: Code library: framework for optimizing prompts and LLM programs. Letta: Agent server and SDKs: agents with persistent memory. Languages — DSPy: Python. Letta: Python and TypeScript SDKs. Licence — DSPy: MIT. Letta: Apache 2.0. Managed / paid option — DSPy: None. Letta: Letta API: free tier, Pro $20/month plus usage. Project status — DSPy: Active; 3.x. Letta: Active.

DSPy vs Letta: which is cheaper?⌄

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

Which is rated higher, DSPy or Letta?⌄

In our catalog, DSPy rates 4.2 out of 5 and Letta rates 4.0 out of 5, so DSPy has a slight edge on reviews.

When should I skip both DSPy and Letta?⌄

Skip DSPy if you don’t have an evaluation set yet. DSPy’s optimizers need one to work. Skip Letta if you only need short-lived task agents. A lighter SDK is simpler.

Sources · tool facts checked October 2026