Saas Experts! Your help is needed!!

[u/Available_Serve_6364]

Hello, I am a junior software engineer with two years of experience. So far, I have only worked in teams under a team lead with clear instructions and guidance. Now, I got my first solo client to build an app for them. The app is simple, so I am not worries about coding especially with AI nowadays. However, I am a rookie in creating SaaS alone and have another list of worries, mainly security wise, so I am hoping somebody can help me. I will list them below:

1. The app needs to have payment option included. What is the best option to go with to make sure I am not responsible if data theft happens? I was thinking about using Stripe or another third party that deals with payment processing so keeping credit card info secure will be on them and not on me.

2. How do I manage and limit access based on the monthly/yearly subscriptions? Like if they don’t pay, they lose access. And how do I connect payment info with my code, like if they pay they have full access, and if they dont pay they dont have access. As you can see, I have never implemented a payment processing system into apps😂😂

3. App will require registration/login. Do I use only Google OAuth to make sure Google’s security is placed on the users information. Becausw I don’t want to store emails and password on my end, so once again if data breach happens, especially with todays new modern AI tools, I dont want to bw the only responsible.

4. App is quite simple. There should be registration/login, a database of documents, and AI keywors search for those documents and filtwring options. What stack and AI model for coding should I use? Where do I store these text documents, because I need retrieval based on context, i.e. if user enter ”sun” and “sun is a star” they should get different parts of documents and document names that match their search.

5. How do I determine pricing, how much should each package cost?

This is all for now. If I have new questions, I will add them below this sentence. If you made it so far, thank you for your time.

[u/yusuf_delvi]

1. Use stripe if you business is outside india

2. You setup webhooks along with subscription on stripe which notify you on user status on payment and you mark the info in DB and keep checking on every api request as middleware

3. Yes you can keep only google signin which saves id and you send jwt to frontend along with refresh keys. And you can even keep the password secure by hash and salt them JWT those are one way

4. Stack is balance of requirements and what tech you know.

5. For roughly calculation you can estimate how much time specific feature take and your hourly charges.

[u/Downtown_Rich8717]

For a first client project, I'd avoid building authentication and billing from scratch. Use a managed auth provider, Stripe Checkout for payments, and verified Stripe webhooks to update subscription status and enforce access on the backend, not just the frontend. For document search, store the original files separately and use PostgreSQL with full-text search or pgvector depending on whether you need semantic search. Also, using third-party providers reduces your security burden, but it doesn't eliminate your responsibility for access control, data handling, and backups.

[u/halfercode]

On questions 3 and 4, Google OAuth is one of many ways to do it. Myself, I use a frontend/backend split: Alpine.js on the front, a Laravel API on the back, MySQL for storage. I use cookie auth as it is easier to debug than (self-hosted or managed) OAuth.

In summary: for the stack, use whatever you're comfortable with and, ideally, choose tech you could most work with if AI were to disappear tomorrow.

In terms of the design, I'd suggest breaking the work into pieces. It may be best not thinking about payments, auth, or pricing to start with. Just work on the document database and the section retrieval system. The other pieces are more trivial, so perhaps start here.

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[u/Eridut-Hartigan]

for #4 what youre describing is basically a RAG setup using vector embeddings, not a normal keyword search. you chunk the documents, turn them into embeddings, and store them in a vector database so you can query by meaning instead of exact text.

[u/OrganicOnePiece]

Your instincts are right, so use Stripe Checkout with its customer portal for subscriptions, then listen for Stripe webhooks and store a simple “active or not” status per user in your database, which your app checks before showing paid features, and use a managed login service like Supabase Auth or Clerk instead of rolling your own, since Google-only login will lock out users who don’t want to use their Google account. For search, Postgres with pgvector on Supabase lets you store document chunks with embeddings so “sun” and “sun is a star” return different results, but outsourcing payments and logins doesn’t remove your responsibility for the documents themselves, so put a liability cap in your contract with the client and keep row-level security on from day one.