Watchtower
Moderates 12M live video streams daily, where the cost of a slow moderation decision is measured in harmful broadcast exposure.
Engineering highlights
The core architectural breakthroughs.
High-scale engineering demand distilled into four verified production milestones.
Violation detection accelerated from 4.2 minutes to 1.8 seconds
Asynchronous keyframe ingestion across 95,000 concurrent broadcasts
Hierarchical tiered model invocation cut monthly spend by $928,000
Cryptographic video snippet proofs retained for appeal compliance
Executive overview
The engineering challenge & solution.
Moderating 12 million daily live video broadcasts against copyright infringement, violence, and brand safety violations. Legacy moderation sampled streams every 4 minutes; harmful broadcasts stayed live for thousands of concurrent viewers before being terminated. Meanwhile, running full transformer vision models on all frames would have cost over $13M annually in GPU compute.
We built a tiered hierarchical computer vision and audio pipeline. An ultra-lightweight edge classifier analyzes video streams at 0.5 FPS alongside audio transcripts. When anomaly probability scores exceed 15%, the stream is seamlessly escalated to high-density GPU nodes running temporal multi-modal transformers.
Engineering governance
The three non-negotiables.
These are the architectural constraints that shaped every boundary — no trade-offs or compromises permitted.
Sub-2-Second Detection Lag
From harmful broadcast occurrence to stream takedown or human escalation must complete in under 2 seconds.
Adaptive Compute Scaling
Scale GPU processing dynamically so 95% of safe streams consume minimal compute while high-risk streams receive full multi-modal analysis.
Immutable Appeal Audit Trail
Store cryptographic proof of video frames and moderation logic for regulatory compliance and creator appeals.
Dynamic Compute Allocation and Synchronous Stream Ingestion Across 80,000 Concurrent Live Broadcasts
Managing 80,000 simultaneous live RTMP/WebRTC streams with variable bitrates created severe network socket exhaustion and memory fragmentation across the video ingestion fleet.
We developed an asynchronous streaming ingestion daemon in Go that pulls keyframes directly from video demuxers without decoding the full video bitstream. Kafka partition keys distribute streams across GPU worker pools based on creator trust scores, optimizing GPU utilization and preventing backlog queuing.
Request lifecycle
How data moves through Watchtower.
Production verification
Measured outcomes in production.
Every metric below was captured under real production traffic and audited against historical baseline data.
Operational resilience
Automated safety guardrails.
Systems fail in production. Here is how Watchtower survives network partitions, upstream timeouts, and anomalous inputs without human intervention.
Human Review Escalation Buffer
Borderline policy takedowns route to priority 30-second human review consoles.
WORM Immutable Storage
Flagged video snippets stored in Write-Once-Read-Many cloud storage for audits.
Automatic Stream Shadowing
Disputed streams kept in temporary cache for instant restoration upon appeal.
Next step
Building a system with this level of demand?
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