Changelog
Track all the latest content additions and updates to Hello Interview. We continuously add new system design breakdowns, deep dives, and learning materials.
June 8 - 14, 2026
2 updatesUpdated Content
Saga pattern and durable execution mechanics overhaul, simplified tooling guidance, and clarity edits based on reader feedback.Jun 11, 2026 by Stefan Mai | System Design
Edits for clarity and correctness, distributed locks overhaul, and expanded sections based on reader feedback.Jun 11, 2026 by Stefan Mai | Deep Dive
June 1 - 7, 2026
1 updatesUpdated Content
Rewrote the pattern around closing the read-modify-write gap, walking up from conditional writes through pessimistic locking, optimistic concurrency, SERIALIZABLE isolation (now covering write skew), and distributed locks as out-of-database leases for reservations. Moved distributed transactions (2PC and sagas) out to the Multi-step Processes pattern so this one stays focused on coordinating access to a single source of truth.Jun 5, 2026 by Evan King | System Design
May 25 - 31, 2026
5 updatesNew Videos
May 25, 2026 by Shivam Chauhan | Content
May 25, 2026 by Shivam Chauhan | Content
May 25, 2026 by Shivam Chauhan | Content
May 25, 2026 by Shivam Chauhan | Content
May 25, 2026 by Shivam Chauhan | Content
May 18 - 24, 2026
11 updatesNew Content
Design ChatGPT
May 21, 2026 by Evan King | System DesignPremium
May 21, 2026 by Stefan Mai | Content
May 21, 2026 by Stefan Mai | Content
May 21, 2026 by Stefan Mai | Content
May 21, 2026 by Stefan Mai | Content
May 21, 2026 by Stefan Mai | Content
May 21, 2026 by Shivam Chauhan | Content
May 21, 2026 by Stefan Mai | Content
May 21, 2026 by Stefan Mai | Content
New Videos
May 24, 2026 by Shivam Chauhan | Content
May 21, 2026 by Shivam Chauhan | Content
May 11 - 17, 2026
10 updatesNew Content
May 14, 2026 by Stefan Mai | ML System Design
New Videos
May 15, 2026 by Shivam Chauhan | Content
May 15, 2026 by Shivam Chauhan | Content
May 14, 2026 by Shivam Chauhan | Content
May 14, 2026 by Shivam Chauhan | Content
May 13, 2026 by Shivam Chauhan | Content
May 13, 2026 by Shivam Chauhan | Content
May 12, 2026 by Shivam Chauhan | Content
May 12, 2026 by Shivam Chauhan | Content
May 11, 2026 by Shivam Chauhan | Content
May 4 - 10, 2026
6 updatesNew Content
May 8, 2026 by Evan King | Content
New Videos
May 10, 2026 by Shivam Chauhan | Content
May 10, 2026 by Shivam Chauhan | Content
May 6, 2026 by Shivam Chauhan | Content
May 5, 2026 by Shivam Chauhan | Content
May 4, 2026 by Shivam Chauhan | Content
April 27 - May 3, 2026
4 updatesNew Videos
May 3, 2026 by Shivam Chauhan | Content
Apr 30, 2026 by Shivam Chauhan | Content
Apr 29, 2026 by Shivam Chauhan | Content
Apr 29, 2026 by Shivam Chauhan | Content
April 20 - 26, 2026
1 updatesNew Content
Apr 24, 2026 by Stefan Mai | ML System Design
April 6 - 12, 2026
4 updatesNew Videos
Apr 12, 2026 by Shivam Chauhan | Content
Apr 9, 2026 by Shivam Chauhan | Content
Apr 9, 2026 by Shivam Chauhan | Content
Apr 9, 2026 by Shivam Chauhan | Content
March 23 - 29, 2026
4 updatesNew Content
Mar 23, 2026 by Evan King | Blog
New Videos
Mar 26, 2026 by Shivam Chauhan | Content
Mar 24, 2026 by Shivam Chauhan | Content
Mar 23, 2026 by Shivam Chauhan | Content
March 16 - 22, 2026
2 updatesNew Videos
Mar 22, 2026 by Shivam Chauhan | Content
Mar 16, 2026 by Shivam Chauhan | Content
March 9 - 15, 2026
11 updatesNew Content
Mar 15, 2026 by Austen McDonald | Behavioral
Mar 15, 2026 by Austen McDonald | Behavioral
Mar 15, 2026 by Austen McDonald | Behavioral
Mar 15, 2026 by Austen McDonald | Behavioral
Mar 15, 2026 by Austen McDonald | Behavioral
Mar 15, 2026 by Austen McDonald | Behavioral
Mar 15, 2026 by Austen McDonald | Behavioral
Mar 15, 2026 by Austen McDonald | Behavioral
Special Interview Types
Mar 15, 2026 by Austen McDonald | BehavioralPremium
New Videos
Mar 14, 2026 by Shivam Chauhan | Content
Mar 9, 2026 by Shivam Chauhan | Content
March 2 - 8, 2026
4 updatesNew Videos
Mar 6, 2026 by Shivam Chauhan | Content
Mar 5, 2026 by Shivam Chauhan | Content
Mar 4, 2026 by Stefan Mai | System Design
Mar 4, 2026 by Shivam Chauhan | Content
February 23 - March 1, 2026
5 updatesNew Videos
Feb 27, 2026 by Shivam Chauhan | Content
Feb 24, 2026 by Shivam Chauhan | Content
Feb 24, 2026 by Shivam Chauhan | Content
Updated Content
Added geospatial indexing section covering geohashes, quadtrees, k-d trees, and R-trees.Feb 26, 2026 by Evan King | Deep Dive
Added geospatial search section covering geo_point, geo_shape, and spatial indexing strategies.Feb 26, 2026 by Stefan Mai | Deep Dive
February 16 - 22, 2026
10 updatesNew Content
Feb 20, 2026 by Evan King | Blog
Feb 20, 2026 by Evan King | Blog
Feb 17, 2026 by Evan King | Blog
Updated Content
Clarified why state-heavy connections favor consistent hashing over pub/sub, fixed misleading Zookeeper lookup description.Feb 17, 2026 by Stefan Mai | System Design
Clarified SSE unidirectional nature, explained gRPC-Web browser limitations, expanded CDC/search index staleness explanation, added eventual vs weak consistency distinction, and introduced PACELC theorem.Feb 16, 2026 by Evan King, Stefan Mai | Quick Guide
Fixed 30%→60% math error in DB5 addition example, corrected virtual node positions to match diagram, added hot spots section with mitigation strategies, added data movement vs replication callout, clarified virtual nodes help with insertions too, added Redis hash slot comparison, and added DDIA caveat about real-world usage.Feb 16, 2026 by Evan King | Deep Dive
Fixed cache latency to say cross-AZ instead of cross-region, clarified cache throughput (reads/writes roughly equal at 100k-200k+ ops/sec), fixed TiB label to tebibytes, changed app server 'sharding' to 'horizontal scaling', updated network to 25 Gbps standard/50-100 Gbps high-perf, aligned message queue WPS threshold with DB limits, and added HA vs sharding callout.Feb 16, 2026 by Evan King | Deep Dive
Fixed factual errors: Erlang still powers WhatsApp, corrected DynamoDB transaction limits and partition/sort key terminology, rewrote pub/sub partitioning scenarios with accurate channel math, fixed Redis memory estimates, and resolved API return type inconsistency.Feb 16, 2026 by Stefan Mai | System Design
Added available_seats > 0 guards to all SQL examples, fixed deadlock ordering advice, corrected REPEATABLE READ claims for PostgreSQL, added row count checks to OCC examples, rewrote ABA/version column guidance, fixed 2PC section (PREPARE TRANSACTION, blocking vs inconsistency), reclassified CockroachDB, added saga orchestrator durability, added fencing tokens for distributed locks, and replaced undefined 'application-level status coordination' term.Feb 16, 2026 by Evan King | System Design
Rewrote sync/async replication section for clarity, fixed auction concurrency example with proper WHERE conditions, clarified read vs write performance numbers, corrected WAL flush explanation, added connection pooling discussion, added optimistic concurrency control section, and removed leftover editorial text.Feb 16, 2026 by Evan King | Deep Dive
Stay Updated
We're constantly adding new content to help you ace your interviews. Check back regularly for the latest system design breakdowns, deep dives, and interview preparation materials.