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

Braintrust: Pricing, Features & Alternatives

Braintrust starts from evaluation rather than tracing: experiments, datasets, scorers and a playground for comparing prompts and models side by side, with production logging on the same data. Every plan has unlimited users. The free Starter plan includes 1 GB of processed data and 10k scores with 14-day retention. Pro is $249/month for 5 GB and 50k scores, then $3/GB and $1.50 per 1,000 scores, and qualifying startups can get 6–12 months of Pro free. It is closed source; there is no self-hosted tier below Enterprise.

Braintrust Pricing Plans (2026)

Plan	Price	Highlights
Starter	$0	1 GB processed data (+$4/GB) · 10k scores (+$2.50 / 1k) · 14-day retention
ProPopular	$249 / month	5 GB processed data (+$3/GB) · 50k scores (+$1.50 / 1k) · 30-day retention
Enterprise	Custom	Custom data and retention · Hybrid / self-hosted deployment

Pricing summary: Free · paid from $249/mo. Always confirm current pricing on the official site.

Key Braintrust Features

5 GB processed data (+$3/GB)
50k scores (+$1.50 / 1k)
30-day retention
Unlimited users
6–12 months free for qualifying startups

Pros

+Strongest eval and experiment workflow in the category
+Unlimited users, so PMs and domain experts can review outputs
+Generous startup program

Cons

−$0 to $249 is a steep step with nothing in between
−Closed source, and only Enterprise can self-host
−Short default retention on both self-serve plans

Best Braintrust Alternatives

Compare all

Langfuse

Free · paid from $29/mo

LangSmith

Free · paid from $39/seat/mo

OpenTelemetry

Free

Braintrust Compared

Braintrust vs Langfuse Braintrust vs OpenTelemetry Braintrust vs LangSmith

Braintrust FAQ

What is Braintrust used for?⌄

Braintrust is a llm observability & evals tool. Eval-first AI observability with unlimited users on every plan. It is priced on data processed and scores run, not seats.

Is Braintrust free?⌄

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

How much does Braintrust cost?⌄

Braintrust offers a free tier, with paid plans starting at $249/month. Some plans are usage-based (pay-as-you-go).

What are the best Braintrust alternatives?⌄

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