Principal / Senior Software Engineer at Flagship Pioneering, Inc.
Cambridge, MA
$108,000–$209,000from the description
Jul 29, 2026
Cambridge, MA
Sep 24, 2026
What this job asks for AI summary
This full-stack software engineering role at an early-stage AI startup focuses on building consumer-facing features across the front-end and back-end of a psychological wellbeing platform. The engineer will own the full product development lifecycle — from architecture and implementation to release management and iteration — while leveraging AWS infrastructure and integrating AI/LLM-powered services. It suits an entrepreneurial generalist comfortable leading technical decisions in a fast-moving, multidisciplinary environment.
Senior level · 5+ years · Full-time
Advertised as Principal, but the requirements read as Senior.
“or” means any one of them counts — you don't need all of them.
We read this from the posting text with AI. Skim the description below before ruling yourself out.
How this req sits in the market our data
Most people in this occupation already list these. Still required — just not what gets you shortlisted.
What the occupation pays Median $138,970 (middle half $107,524–$175,762). This posting is about at that midpoint.
Estimated from BLS employment for this occupation and area, per-skill prevalence across our listing corpus, and published wage benchmarks — as of Aug 1, 2026. It is a model, not a headcount.
Why we read it this way (6)
The title is listed as 'Principal / Senior Software Engineer' — the advertised level is Principal (the higher of the two named), but the requirements (5+ years, standard full-stack scope) support a Senior classification.
No specific work location or metro area is stated in the posting; the CBSA fields are left blank accordingly.
AWS-specific services (ECS, S3, Lambda) appear as illustrative examples within the required AWS experience, not as individually gated requirements; they are captured as preferred to reflect that nuance.
CI/CD is listed as a key responsibility with firm language ('implementing continuous integration, continuous delivery') in the core duties section, treated as a hard gate.
AWS Certifications are listed under Preferred Qualifications and are omitted from the skills list as they are credentials rather than concrete technologies.
Security best practices for SaaS appear under Preferred Qualifications and are omitted as they name no specific tool or technology.
Read the full posting
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