How to self-host your Jira alternative
Jira is known for its configurable complexity, and the catalog's 3 self-hosted alternatives aren't interchangeable with each other — each is built for a different level of that complexity, not as a general Jira replacement.
Tools that meet this intent
Alternative to Jira, Asana, Linear
Project and issue management, an alternative to Jira and Asana.
Alternative to Jira
Agile management (Scrum/Kanban), a simpler alternative to Jira.
Alternative to Jira, MS Project
Project management with Gantt and budgets, an alternative to Jira/MS Project.
Real server requirements
Between 512MB and 2GB of RAM depending on the tool — never a single number.
Taiga covers agile management with Scrum and Kanban, backlog and user stories — documented in its own catalog entry with a "much smaller learning curve than Jira," built for teams who want that simplicity without the rest of Jira's machinery. OpenProject goes the opposite direction: besides agile backlogs it adds interactive Gantt charts and time tracking with budgets — the project specifies it's "the most complete for traditional + agile project management," built for larger teams with more formal planning needs than standard Jira usage.
Plane sits in between the two: cycles, modules and Kanban/list/calendar/Gantt views with a more modern interface, without reaching OpenProject's depth on budgets and time tracking, and without staying at Taiga's deliberate simplicity. All 3 tools are self-hostable with Docker and use PostgreSQL as their database.
What you gain and lose versus the SaaS
Fit depends on the team's own way of working: one that ran basic Kanban/Scrum in Jira will likely find everything OpenProject adds overkill; one that relied on Gantt charts and budgets in Jira probably does need it, and Taiga wouldn't give them that.