How We Keep Mobile Session Replay 17x Cheaper Than PostHog
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Practical cost optimization for session replay, actionable.
Rejourney achieves 17-20x cost savings over PostHog for mobile session replay through a stack of engineering decisions: capturing at 1.25x scale (vs. native resolution), limiting to 1 FPS with run-loop-aware timers, background encoding with hard backpressure limits, on-device redaction before JPEG encoding, and binary frame bundles compressed with gzip level 9. These choices reduce pixel count by ~5.8x before compression, minimize upload bandwidth, and eliminate server-side blurring pipelines, making the economics sustainable at scale.
- Apply aggressive client-side compression (e.g., lower resolution, lower FPS, on-device redaction) and backpressure to minimize data volume before it hits your infrastructure, compounding savings across bandwidth, storage, and compute.
For a senior engineer building scalable systems, these architectural patterns—aggressive client-side compression, throttling, and backpressure—directly reduce storage and egress costs, a critical consideration when designing data-intensive products.
Mohammad R. Rashid