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.

Agent Auth & Tool CallingFree tier

ACI.dev: Pricing, Features & Alternatives

ACI.dev (Agent-Computer Interface) is an Apache-2.0 platform that connects agents to 600+ tools through direct function calling or one unified MCP server. It includes multi-tenant OAuth flows and secrets management for each of your end users, dynamic tool discovery, and natural-language permission boundaries on what an agent may do. You can run the full backend and frontend yourself or use the managed service at aci.dev. It is the most permissively licensed option in this category, but the main repository has had no commits since May 2026, so check its activity before you depend on it.

ACI.dev Pricing Plans (2026)

Plan	Price	Highlights
Open sourcePopular	$0 (Apache-2.0)	600+ integrations · Multi-tenant OAuth · Unified MCP server
Managed	See vendor	Hosted at aci.dev

Pricing summary: Free · then usage-based. Always confirm current pricing on the official site.

Key ACI.dev Features

600+ integrations
Multi-tenant OAuth
Unified MCP server
Self-hosted

Pros

+Apache-2.0: truly open source and self-hostable
+Multi-tenant OAuth for end users built in
+One MCP server for all tools

Cons

−No commits to the main repo since May 2026
−Smaller catalog than hosted rivals
−You run and secure the token store yourself

Best ACI.dev Alternatives

Compare all

Composio

Free · paid from $29/mo

Arcade

Free · paid from $25/mo

Nango

Free · paid from $50/mo

ACI.dev Compared

ACI.dev vs Composio ACI.dev vs Arcade ACI.dev vs Nango

In-depth guideComposio vs Arcade (2026): Agent Auth & Tool Calling, Plus Open-Source Nango and ACI.devYour agent has to act inside Gmail, Slack and Salesforce as each of your users, without the model seeing a token. Composio and Arcade compared with Nango and ACI.dev on OAuth handling, licence and cost at 50 and 1,000 users.

ACI.dev FAQ

What is ACI.dev used for?⌄

ACI.dev is a agent auth & tool calling tool. Open-source (Apache-2.0) tool-calling platform: 600+ integrations, multi-tenant OAuth for end users, and a unified MCP server.

Is ACI.dev free?⌄

Yes — ACI.dev has a free tier you can start with, and paid plans for more usage and features.

How much does ACI.dev cost?⌄

ACI.dev is free to use, with usage-based pricing on some features.

What are the best ACI.dev alternatives?⌄

Popular ACI.dev alternatives include Composio, Arcade, Nango. Compare pricing and features on our ACI.dev alternatives page.