Software Engineer, Platform​/Applied AI; Full-Stack

After Query — Software Engineer, Platform / Applied AI (Full-Stack)

Type: Full-time | On-site | San Francisco, CA
Compensation: $180,000–$220,000 + Competitive equity (4-year vest)
Hiring count: 4
Visa sponsorship: O-1, OPT
Reports to: Interviews run by Alec (Initial Screen) and an engineer (Second Round); founding-team reporting line — confirm

After Query is a research lab investigating the boundaries and capabilities of AI through novel datasets and experimentation. Its customers are the foundation-model labs — it serves the frontier AI labs. Backed by top investors including Y Combinator and Box Group, ex-partners from Lightspeed and Index Ventures, and senior leadership at Google Deep Mind and Meta GenAI. The founding team brings backgrounds from Jane Street, Meta, Citadel Securities, Google, Goldman Sachs, Morgan Stanley, Silver Lake, Berkeley AI Research (BAIR), and the Stanford AI Laboratory (SAIL).

Reported $25M+ annualized revenue and one of the fastest-growing companies in its YC batch.

Founded: 2025 | Team size: 11–50 | Stage:
Series A (company card) — outreach describes it as "seed-stage"; confirm

Industry: AI research / data infrastructure for frontier labs Website: after query.com Office:
San Francisco, CA

• Founding ownership: One of the first hires; own entire projects end-to-end and define/own the data infrastructure from day one, with immediate visible impact.
• Frontier impact: Build the data infrastructure shaping frontier-model development, with the frontier AI labs as direct customers.
• Trajectory & backing: One of the fastest-growing companies in its YC batch, $25M+ annualized revenue, elite founding team and investors, with a path to lead and grow an engineering team as they scale.
• Comp & perks: Competitive salary + equity (4-year vest), daily lunch & dinner covered, free gym membership, health insurance.

As a core/founding engineer, you’ll build the data infrastructure shaping frontier-model development, owning projects end-to-end across frontend, backend, and infrastructure.

• Build and scale complex data-capture workflows across web (Next.js) and desktop (Python)
• Architect and optimize high-throughput data pipelines under heavy load
• Collaborate with the founding team to define product strategy and ship features fast
• Set engineering best practices and lay the groundwork for future team growth

Tech stack: Next.js / JavaScript / Type Script, Python, Go
· GCP/AWS (serverless, cloud functions)
· Kubernetes
· Redis
· Elasticsearch
· Kafka / RabbitMQ
· No

SQL
· APIs

• Proficiency in JavaScript (Next.js) and Python, with demonstrated experience building full-stack web applications
• Experience with serverless architecture and cloud functions for heavy data processing (GCP/AWS)
• Storage, caching & search: hands-on with Redis (caching), Elasticsearch (indexing), and message queues (Kafka/RabbitMQ) to build scalable, low-latency pipelines
• Any background in AI research, LLM evaluation, or human-in-the-loop systems
• Experience getting your ideas into production (founder experience preferred)

• Must come from a top university (US/Canadian/UK), top quant firm, or have founding engineer experience.
• Strong coding fundamentals in Node.js / Type Script, Python and/or Go.
• Deep understanding of distributed systems, scalability challenges, and system design.
• Familiarity with cloud platforms (GCP/AWS), Kubernetes, APIs, No
  
  SQL databases.
• Ability to reason about trade-offs and balance speed vs reliability.
• Strong communication skills and a bias toward ownership, curiosity, and delivering simple solutions to complex problems.
• Bonus:
  Experience with RL environments, agentic systems, or human-in-the-loop workflows.

Salary $180,000–$220,000

Equity Competitive (4-year vest)
Experience0–4 years

On-site policy

On-site, San Francisco Visa sponsorshipO-1, OPT

Employment type

Full-time

Location

San Francisco, CAOpenings4