#87
B+
Rank #71
Mattermost
Open-source Slack alternative with channels, threads, and enterprise SSO/compliance features. Solid Go architecture, though true high-availability clustering adds real operational complexity.
74.3
/ 100
⚙ Full Stack
Go monolith backend, React/TypeScript client, Postgres or MySQL for persistence, optional Redis/Elasticsearch for caching and search at scale.
📈 Scaling Analysis
Go's concurrency model and Postgres backing give it real horizontal-scale legs, and Mattermost documents an actual HA clustering mode — but licensing gates some HA features to Enterprise, and self-managed clustering config is nontrivial to get right.
🚀 Running on Nexlayer
App pod plus a postgres pod covers small teams; SiteURL must be set to the Nexlayer domain and the DB DSN pointed at postgres.pod:5432. mirror.gcr.io/library/postgres works for the DB image; HA clustering needs a shared file store (S3-compatible) that Nexlayer would need to provide externally.