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.

LLM Observability & EvalsFree tier

LangSmith: Pricing, Features & Alternatives

LangSmith comes from the team behind LangChain and LangGraph, and it shows: agent graphs, tool calls and state transitions render without extra instrumentation, and it now ingests OpenTelemetry for everything else. The free Developer plan is one seat with 5,000 base traces a month. Plus is $39 per seat with 10,000 traces and pay-as-you-go above that. Base traces keep 14 days; 180-day extended retention costs more per trace. LangChain has repriced traces more than once in 2026, so model your volume in its calculator. Self-hosting is an Enterprise option.

LangSmith Pricing Plans (2026)

Plan	Price	Highlights
Developer	$0 (1 seat)	5,000 base traces / month · 14-day retention · 1 seat
PlusPopular	$39 / seat / month	10,000 base traces / month included · Pay as you go beyond that · Unlimited seats
Enterprise	Custom	Custom trace allowances · Self-hosted or hybrid deployment · SSO and SLAs

Pricing summary: Free · paid from $39/seat/mo. Always confirm current pricing on the official site.

Key LangSmith Features

10,000 base traces / month included
Pay as you go beyond that
Unlimited seats
Extended 180-day retention available

Pros

+Best-in-class visibility into LangGraph and LangChain agents
+Mature evals, datasets and annotation queues
+Accepts OpenTelemetry traces from non-LangChain code

Cons

−Per-seat and per-trace pricing both scale with you
−Trace pricing has changed repeatedly, so budgets drift
−Self-hosting requires an Enterprise contract

Best LangSmith Alternatives

Compare all

Langfuse

Free · paid from $29/mo

Braintrust

Free · paid from $249/mo

OpenTelemetry

Free

LangSmith Compared

LangSmith vs Langfuse LangSmith vs Braintrust LangSmith vs OpenTelemetry

LangSmith FAQ

What is LangSmith used for?⌄

LangSmith is a llm observability & evals tool. LangChain's tracing and evaluation platform, the deepest fit for LangGraph agents. It is priced per seat plus per trace.

Is LangSmith free?⌄

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

How much does LangSmith cost?⌄

LangSmith offers a free tier, with paid plans starting at $39/month. Some plans are usage-based (pay-as-you-go).

What are the best LangSmith alternatives?⌄

Popular LangSmith alternatives include Langfuse, Braintrust, OpenTelemetry. Compare pricing and features on our LangSmith alternatives page.