Relixir (YC X25)
Founding Engineer – Backend & AI Systems
Relixir (YC X25), San Francisco, California, United States, 94199
Join to apply for the
Founding Engineer – Backend & AI Systems
role at
Relixir (YC X25) Join to apply for the
Founding Engineer – Backend & AI Systems
role at
Relixir (YC X25) Get AI-powered advice on this job and more exclusive features. This range is provided by Relixir (YC X25). Your actual pay will be based on your skills and experience — talk with your recruiter to learn more. Base pay range
$150,000.00/yr - $250,000.00/yr Location:
In-person, SF\ \
Requirement:
BS in Computer Science from Top US Unverisity (Stanford, Berkeley, MIT, GeorgiaTech, etc.)
Stack:
Python, FastAPI, PostgreSQL, AWS (ECS, Fargate), Qdrant, TypeScript
Backend Infrastructure
What You’ll Work On
Building and scaling services in Python (FastAPI) with PostgreSQL as our primary database. Managing AWS infrastructure — primarily ECS/Fargate, Lambda, S3, and related services. Designing APIs for our frontend (TypeScript) and partner integrations.
AI/ML Engineering
Building agentic workflows and pipelines for large-scale LLM calls (OpenAI, Gemini, Perplexity). Designing and maintaining RAG (Retrieval-Augmented Generation) systems using Qdrant for vector search. Optimizing prompt engineering, retrieval strategies, and evaluation systems.
The ROLE
You are
not
just an employee – you are a builder of the company.
You’ll be at the core of shaping Relixir’s product, technology, and trajectory – from hands-on backend and AI engineering, to collaborating on the big decisions that define our future.
Strategic Impact – Work directly with the founders to influence technical and product direction, deciding how we scale our platform and what bets we make in AI search automation. End-to-End Ownership – Take ideas from rough concept to production-ready systems – APIs, infrastructure, AI agents, and everything in between. You’ll own critical backend modules and ensure they’re fast, reliable, and a joy to use. AI Systems Engineering – Design and deploy large-scale AI workflows – multi-agent pipelines, RAG architectures with Qdrant, and high-volume LLM call orchestration. Customer-Driven Development – Talk to customers, dig into their needs, and turn feedback into technical solutions that directly impact their growth.
About You
Deeply Curious — You actively seek to understand complex systems, customer problems, and the latest technical possibilities. Curiosity drives your best work. Relentlessly Driven — You thrive in early-stage chaos. You move quickly, test bold ideas, and turn uncertainty into working solutions. True Owner — You don’t just “complete tickets.” You take full responsibility for delivering outcomes — finding a path forward even with incomplete information. Collaborative & Humble — You share ideas openly, listen actively, and care more about the best solution than being right. You’re confident in your skills but always learning.
Must-Haves
In-person SF High-agency 3+ years of experience building backend & AI software for VC-backed startups Strong proficiency in Python and TypeScript Experience with Docker, FastAPI, PostgreSQL, and AWS Built and deployed a complex agentic/LLM-backed (context engineering, RAG with vector db) into production to customers Have completed at least one 0 -> 1 journey of a functional product
Nice-to-haves
Experience working with any of AWS ECS + SQS + Fargate, QDrant, LangChain Entrepreneurial Mindset: Ex-founder or future founder
Why This Role is Special
We're Growing 166% MoM, Onboarding Monster Logos (Rippling, Airwallex, Hackerrank, Etc.), Supporting Global Marketing Teams, And On Our Way To Series A By EOY.\ \ This August, I'm Looking For The Most Cracked Top 1% Founding Engineers And Founding Customer Success/ops To Join Our Rocketship \ \ \ Here's My Pitch To You
Our product is far ahead of the competition. Companies are switching to us every week because they see the differentiation & immediate value. Revenue pipeline is already at $X,000,000
Customers now see Relixir as the unified solution to automate their entire SEO/GEO Growth Marketing function: a $400B market opportunity. We're backed by Y Combinator and legendary operating investors like z21 Ventures who have built unicorns from scratch.\ \ \ Lastly, our team is a group of nonchalant, hardworking, super chill college dropouts from Berkeley who have scaled and even exited previous companies for 7-figures.
Seniority level
Seniority level Mid-Senior level Employment type
Employment type Full-time Job function
Job function Engineering and Information Technology Industries Software Development Referrals increase your chances of interviewing at Relixir (YC X25) by 2x Get notified about new Back End Developer jobs in
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Founding Engineer – Backend & AI Systems
role at
Relixir (YC X25) Join to apply for the
Founding Engineer – Backend & AI Systems
role at
Relixir (YC X25) Get AI-powered advice on this job and more exclusive features. This range is provided by Relixir (YC X25). Your actual pay will be based on your skills and experience — talk with your recruiter to learn more. Base pay range
$150,000.00/yr - $250,000.00/yr Location:
In-person, SF\ \
Requirement:
BS in Computer Science from Top US Unverisity (Stanford, Berkeley, MIT, GeorgiaTech, etc.)
Stack:
Python, FastAPI, PostgreSQL, AWS (ECS, Fargate), Qdrant, TypeScript
Backend Infrastructure
What You’ll Work On
Building and scaling services in Python (FastAPI) with PostgreSQL as our primary database. Managing AWS infrastructure — primarily ECS/Fargate, Lambda, S3, and related services. Designing APIs for our frontend (TypeScript) and partner integrations.
AI/ML Engineering
Building agentic workflows and pipelines for large-scale LLM calls (OpenAI, Gemini, Perplexity). Designing and maintaining RAG (Retrieval-Augmented Generation) systems using Qdrant for vector search. Optimizing prompt engineering, retrieval strategies, and evaluation systems.
The ROLE
You are
not
just an employee – you are a builder of the company.
You’ll be at the core of shaping Relixir’s product, technology, and trajectory – from hands-on backend and AI engineering, to collaborating on the big decisions that define our future.
Strategic Impact – Work directly with the founders to influence technical and product direction, deciding how we scale our platform and what bets we make in AI search automation. End-to-End Ownership – Take ideas from rough concept to production-ready systems – APIs, infrastructure, AI agents, and everything in between. You’ll own critical backend modules and ensure they’re fast, reliable, and a joy to use. AI Systems Engineering – Design and deploy large-scale AI workflows – multi-agent pipelines, RAG architectures with Qdrant, and high-volume LLM call orchestration. Customer-Driven Development – Talk to customers, dig into their needs, and turn feedback into technical solutions that directly impact their growth.
About You
Deeply Curious — You actively seek to understand complex systems, customer problems, and the latest technical possibilities. Curiosity drives your best work. Relentlessly Driven — You thrive in early-stage chaos. You move quickly, test bold ideas, and turn uncertainty into working solutions. True Owner — You don’t just “complete tickets.” You take full responsibility for delivering outcomes — finding a path forward even with incomplete information. Collaborative & Humble — You share ideas openly, listen actively, and care more about the best solution than being right. You’re confident in your skills but always learning.
Must-Haves
In-person SF High-agency 3+ years of experience building backend & AI software for VC-backed startups Strong proficiency in Python and TypeScript Experience with Docker, FastAPI, PostgreSQL, and AWS Built and deployed a complex agentic/LLM-backed (context engineering, RAG with vector db) into production to customers Have completed at least one 0 -> 1 journey of a functional product
Nice-to-haves
Experience working with any of AWS ECS + SQS + Fargate, QDrant, LangChain Entrepreneurial Mindset: Ex-founder or future founder
Why This Role is Special
We're Growing 166% MoM, Onboarding Monster Logos (Rippling, Airwallex, Hackerrank, Etc.), Supporting Global Marketing Teams, And On Our Way To Series A By EOY.\ \ This August, I'm Looking For The Most Cracked Top 1% Founding Engineers And Founding Customer Success/ops To Join Our Rocketship \ \ \ Here's My Pitch To You
Our product is far ahead of the competition. Companies are switching to us every week because they see the differentiation & immediate value. Revenue pipeline is already at $X,000,000
Customers now see Relixir as the unified solution to automate their entire SEO/GEO Growth Marketing function: a $400B market opportunity. We're backed by Y Combinator and legendary operating investors like z21 Ventures who have built unicorns from scratch.\ \ \ Lastly, our team is a group of nonchalant, hardworking, super chill college dropouts from Berkeley who have scaled and even exited previous companies for 7-figures.
Seniority level
Seniority level Mid-Senior level Employment type
Employment type Full-time Job function
Job function Engineering and Information Technology Industries Software Development Referrals increase your chances of interviewing at Relixir (YC X25) by 2x Get notified about new Back End Developer jobs in
San Francisco, CA . San Francisco, CA $150,000.00-$230,000.00 4 months ago Full-Stack Software Engineer (Jr/Mid level)
San Francisco, CA $163,000.00-$225,000.00 2 weeks ago San Francisco, CA $150,000.00-$260,000.00 5 days ago San Francisco, CA $140,000.00-$210,000.00 4 months ago San Francisco, CA $120,000.00-$190,000.00 9 months ago San Francisco, CA $130,000.00-$185,000.00 3 months ago San Francisco, CA $75,000.00-$150,003.00 11 months ago Backend Engineer/API, Payments and Risk (US)
San Francisco, CA $165,000.00-$165,000.00 2 years ago San Francisco, CA $120,000.00-$180,000.00 2 weeks ago San Francisco, CA $40,000.00-$100,000.00 2 months ago San Francisco, CA $6,000.00-$10,000.00 15 hours ago San Francisco, CA $122,000.00-$142,000.00 3 days ago San Francisco, CA $160,000.00-$230,000.00 2 weeks ago San Francisco, CA $140,000.00-$200,000.00 2 months ago San Francisco, CA $150,000.00-$300,000.00 1 month ago San Francisco, CA $170,000.00-$220,000.00 9 months ago Full-stack Software Development Engineer (FS SDE)
San Francisco, CA $99,998.00-$199,998.00 1 year ago San Francisco, CA $110,000.00-$170,000.00 1 month ago San Francisco, CA $120,000.00-$250,000.00 9 months ago San Francisco, CA $150,000.00-$250,000.00 2 weeks ago San Francisco, CA $60,000.00-$80,000.00 1 month ago We’re unlocking community knowledge in a new way. Experts add insights directly into each article, started with the help of AI.
#J-18808-Ljbffr