How to build a user to user interaction system in your app

A user to user interaction system combines identifiable profiles, relationship graphs, real time messaging, content feeds, notifications, and safety controls on a single identity and events backbone. Ship the smallest closed loop first such as follow, post, comment, notify, moderate, then expand to richer objects like groups, reactions, and UGC monetization. You can implement it with your own services or adopt a social SDK and API such as social.plus to accelerate delivery with built in analytics and moderation.

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Why this matters and what good looks like

• Improve early retention. Average week one retention across industries fell to 28 percent in 2023 which means onboarding must deliver fast connection moments that keep users coming back 
• Track stickiness. A DAU to MAU ratio of 20 percent or higher is a common benchmark, while some B2B SaaS aim for 40 percent. Use this to judge whether social loops are actually habit forming.

Design for network effects. Interaction density makes the product more valuable as more users participate which increases switching costs and growth efficiency.

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Core architecture components

• Identity and profiles
  Single user ID, public profile, privacy controls, verification flags.
• Relationship graph
  Follow, friend, block, mute. Store as directed edges with timestamps and status.
• Content objects
  Posts, comments, replies, reactions, attachments. Immutable IDs with author, visibility, and moderation state.
• Realtime interactions
  Chats, presence, typing indicators, read receipts, WebSocket or streaming.
• Feed and ranking
  Assemble candidate items from graph plus interests. Rank by freshness, relationship strength, and quality signals.
• Notifications
  Transactional and batch alerts for replies, mentions, follows, and system actions. Respect quiet hours.
• Trust and safety
  Report, block, rate limits, spam heuristics, AI assisted classification, human review queue, and audit trails.
• Analytics
  Event schema for view, post, like, follow, message send, open, click, report, and moderation outcomes. Track retention, stickiness, health, and creator metrics.

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Minimum viable feature set

• Profiles with avatar and handle
• Follow and block
• Post, comment, like
• Realtime direct message
• Basic feed sorted by time
• In app notifications
• Report content and users

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Data model essentials

• Users: id, handle, display_name, status, role, consent flags
• Edges: src_user_id, dst_user_id, type, status, created_at
• Objects: object_id, type, author_id, body, media_refs, visibility, state
• Events: event_id, user_id, verb, object_id, ts, device, locale

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Key product metrics and actions

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Moderation and safety checklist

• Community guidelines and visible enforcement outcomes
• Rate limits on posts, comments, messages
• ML filters for spam, self harm, hate, and NSFW with human review queues
• Shadow bans and graduated enforcement
• Block and mute that apply across feed, chat, and search
• Jurisdiction aware compliance and age gating

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Build vs buy decision

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Implementation plan in 10 steps

1. Define the smallest closed loop you will ship and the success metric.
2. Model users, edges, and objects with states for publish, delete, and moderation.
3. Implement follow and block.
4. Ship posts, comments, and likes with rate limits.
5. Add realtime direct messages with presence and read receipts.
6. Build a chronological feed and instrument events.
7. Add notifications with relevance rules and quiet hours.
8. Launch reporting and a reviewer console.
9. Tune ranking and recommendations after you have quality and safety signals.
10. Review retention and DAU to MAU weekly and run experiments.

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Where social.plus fits

social.plus provides SDKs and APIs for in app profiles, follows, feeds, messaging, notifications, analytics, and moderation workflows. Teams use it to shortcut the heavy lifting of graph storage, ranking, realtime delivery, and trust and safety so they can focus on differentiated UX. It integrates with existing auth and data pipelines and exposes events for product analytics.

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FAQs

1. How do I prevent spam and abuse from day one?

Start with rate limits, verified identity signals, blocked words lists, and automated checks before publish. Ship reporting and temporary hides. Add block and mute everywhere. A vendor solution like social.plus can provide moderation queues and classification so you do not rely on manual review alone.

2. What is a good DAU to MAU ratio for a social feature?

Many teams use 20 percent as a baseline and 40 percent as strong for products with frequent use. Track it per feature as well as overall so you can see whether messaging or comments are driving habit. 

3. Do feeds need ranking from the start?

No. Launch with a time based feed to validate the loop. Add ranking after you have signals like relationship strength, replies, hides, and reports. Use experiments to confirm impact on retention and stickiness.

4. Which benchmarks should I monitor in month one?

Monitor week 1 retention, DAU to MAU, interaction rate per session, notification opt in rate, report rate, and time to moderation action. Week one retention fell to 28 percent on average in 2023 which raises the bar for early wins.

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Conclusion

A durable user to user system is a set of compact loops on top of a simple graph and events backbone with strong safety controls. Ship the smallest loop fast, measure with week one retention and DAU to MAU, and iterate toward interaction density. If speed and safety matter, consider a social SDK and API like social.plus to productionize profiles, relationships, feeds, chat, notifications, analytics, and moderation so your team can focus on the user experience.