Moengage | Tech Lead | Oct 2026 | Rejected
- Experience
- 8 years
- Posted
- 16 Oct 2026
Summary
I interviewed for a Tech Lead role at Moengage in October 2026, cleared multiple rounds including system design and technical deep dive, but was ultimately rejected.
How it went
Company: Moengage Role: Tech Lead
Date: October 2026 Current Org: Startup College: Tier-1 YOE: 8+ Current Comp: ~65L (Cash component) + ESOPs
Round 1 - Hiring Manager (1 hour)
- Intro, behavioral questions, and past project discussions.
Round 2 - LLD
- Design a rate limiter.
Round 3 - HLD
- Task: Design a user data ingestion system for a multi-tenant platform.
- Tenants upload CSV sheets and the system needs to process and insert that data into the database.
Note: Cleared these rounds and got invited for the final rounds in-office.
Round 4 - Technical Deep Dive (In-Office) With a Senior Staff Engineer.
-
I had built an events pipeline in my current org that pushed events to BigQuery from pub/sub. He dug deep into that:
- How to sync user profiles in BigQuery for analytics and manage updates to the profiles.
- How to handle data compaction (I wasn't able to answer this effectively).
-
Database selection: If you need to store 300M users' data, which DB would you pick among PostgreSQL, MongoDB, Spanner, and Cassandra / ScyllaDB?
-
Data ingestion scale: How to update 300M users' data from CSV files into the database (similar to the earlier HLD round).
-
Variation: How the architecture changes if you need to trigger external API calls instead of direct DB writes.
-
Fumble: At one point, I mentioned that PostgreSQL can handle ~10k writes per second based on standard system design handbooks. He immediately drilled down into the specifics: "What exact CPU and RAM specs would you need for that instance?"
Round 5 - Senior VP (In-Office)
- Standard intro and motivation to switch: Why Moengage?
- Behavioral questions: How do you handle conflict? Have you mentored or upskilled engineers to improve their delivery?
Self-reflection: The last two in-office rounds went just average/okayish.
Verdict: Rejected
Questions asked (6)
- 01
Design a Rate Limiter
System Design
Design a rate limiter that can control the number of requests per unit time for a service or API. Consider aspects such as distributed deployment, burst handling, and precision of limiting.
- 02
Design User Data Ingestion System
System Design
Design a user data ingestion system for a multi-tenant platform. Tenants upload CSV sheets and the system needs to process and insert that data into the database, ensuring isolation between tenants and scalability.
- 03
Select Database for 300M Users
System Design
If you need to store data for 300 million users, which database would you choose among PostgreSQL, MongoDB, Spanner, and Cassandra/ScyllaDB? Discuss trade‑offs in terms of scalability, consistency, and operational complexity.
- 04
Update 300M Users Data from CSV
System Design
How would you update 300 million users' data from CSV files into the chosen database at scale? Describe the ingestion pipeline, parallelism, batching, and failure handling strategies.
- 05
Architecture Change for External API Calls
System Design
If the ingestion system needs to trigger external API calls instead of writing directly to the database, how would the architecture change? Discuss impact on latency, throughput, and reliability.
- 06
CPU and RAM Specs for 10k Writes per Second
System Design
What exact CPU and RAM specifications would you need for an instance that must handle approximately 10,000 writes per second, considering the chosen database and workload characteristics?