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.

Google ADK vs Letta: Which is Better in 2026?

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Agent Framework

Choosing between Google ADK 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.

Google ADK is for: Teams on Google Cloud, or working in Java, Go or Kotlin as well as Python, that want multi-agent systems with A2A support.

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 Google ADK if you work in Java or Go, or need the same framework across several languages. Choose Letta if your agent must remember users and past sessions over weeks or months.

Google ADK vs Letta — Side by Side

	Google ADK	Letta
Category	Agent Framework	Agent Framework
What it is	Code library: multi-agent development kit	Agent server and SDKs: agents with persistent memory
Languages	Python, Java, Go, TypeScript, Kotlin	Python and TypeScript SDKs
Licence	Apache 2.0	Apache 2.0
Managed / paid option	Vertex AI Agent Engine (Google Cloud, usage-based)	Letta API: free tier, Pro $20/month plus usage
Project status	Active; 1.x, 2.0 in progress	Active
Pricing	Free · then usage-based	Free · paid from $20/mo
Starting price	Free tier available	Free tier available
Free tier
Rating	4.4	4.0
Best for	Agent Framework — Google Cloud, multi-language, A2A	Agent Framework — long-term memory, stateful agents, self-host or hosted

Pros & Cons

Google ADK

Deep GCP / Vertex AI integration
Strong multi-agent support
Model-agnostic via LiteLLM
Backed by Google

Best value tied to Google Cloud
Younger ecosystem than LangChain

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

Google ADK

SDKs for Python, Java, Go and TypeScript, with Kotlin added later
Multi-agent systems and Agent2Agent (A2A) protocol support
Optimized for Gemini; other models through LiteLLM
Deploy to Vertex AI Agent Engine, Cloud Run or GKE
Apache 2.0 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 Google ADK if…

You work in Java or Go, or need the same framework across several languages.
You’re on Google Cloud and want a managed runtime in Vertex AI Agent Engine.
You need agents that talk to other agents over A2A.

Google ADK 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 Google ADK better than Letta?⌄

What is the difference between Google ADK and Letta?⌄

What it is — Google ADK: Code library: multi-agent development kit. Letta: Agent server and SDKs: agents with persistent memory. Languages — Google ADK: Python, Java, Go, TypeScript, Kotlin. Letta: Python and TypeScript SDKs. Managed / paid option — Google ADK: Vertex AI Agent Engine (Google Cloud, usage-based). Letta: Letta API: free tier, Pro $20/month plus usage. Project status — Google ADK: Active; 1.x, 2.0 in progress. Letta: Active.

Google ADK vs Letta: which is cheaper?⌄

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

Which is rated higher, Google ADK or Letta?⌄

In our catalog, Google ADK rates 4.4 out of 5 and Letta rates 4.0 out of 5, so Google ADK has a slight edge on reviews.

When should I skip both Google ADK and Letta?⌄

Skip Google ADK if you don’t use Google Cloud and want a managed runtime. LangSmith Deployment, CrewAI AMP or Mastra Cloud are options. Skip Letta if you only need short-lived task agents. A lighter SDK is simpler.

Sources · tool facts checked October 2026