Seeking evidence-based recommendations for a mobile-first platform to monitor U.S. equities intraday with low-latency, high-fidelity alerts. I am not looking for general opinions; I’m interested in solutions that can be benchmarked against specific technical criteria and constraints.
Target capabilities
- Data: Real-time SIP vs direct (Nasdaq Basic, NYSE/CTA/UTP), depth-of-book availability, odd-lot handling, auction/imbalance data, halt/resume notices, corporate actions latency.
- Alerts: Server-side evaluation, composable conditions (price, volume rate-of-change, NBBO change, volatility bands, book imbalance), recurrence suppression/de-duplication, pre/post-market support, ability to alert on derived metrics (e.g., 1-second realized volatility, VWAP deviation).
- Latency and reliability: Sub-500 ms median alert latency to reference print during RTH, sub-2 s p95, predictable behavior under degraded networks (LTE vs Wi‑Fi), exactly-once delivery, no missed triggers.
- Coverage and scope: US equities primarily, but optional options chains with Greeks/IV and multi-venue routing indicators.
- Portfolio integration: Read-only broker sync (positions, tax lots), account-agnostic watchlists, cross-device state sync.
- Privacy/security: No third-party ad SDKs or device fingerprinting, encrypted transport, minimal telemetry, clear data provenance and redistribution compliance.
- Resource use: Low battery/CPU under continuous use, efficient streaming vs polling, background refresh policy transparency.
- Cost/compliance: Transparent exchange fees, non-pro vs pro classification handling, fair throttling limits.
If you have a candidate app or stack, please share measured results and implementation notes. To keep responses comparable, please include:
- App/version, platform (iOS/Android), data plan used, declared data sources (e.g., SIP consolidated, IEX, Nasdaq Basic).
- Alert engine type (server-side vs client-side), condition types supported, frequency limits, and whether alerts evaluate on trades, quotes, or both.
- Measured latency: median and p95 notification delay vs an independent reference feed during RTH and pre/post, plus jitter.
- Reliability: Missed-alert rate over N triggers and any dedup behavior under bursty conditions.
- Battery impact: mA or %/hr during a 60-minute streaming session (background and foreground), device model, OS, and network.
- Privacy: Observed network endpoints and telemetry via a proxy, presence/absence of third-party trackers, data retention policy.
Suggested measurement protocol (if helpful):
1) Time-sync device via NTP. 2) Use a high-liquidity symbol (e.g., SPY, AAPL). 3) Set an alert on a narrow threshold expected to trigger frequently. 4) Capture reference prints/quotes from an independent feed and log timestamps. 5) Record alert receipt timestamps across 100+ events on both Wi‑Fi and LTE. 6) Compute median/p95/p99 and missed-alert rate. 7) Log battery draw via iOS Instruments or Android Battery Historian. 8) Inspect outbound telemetry with a local MITM proxy (where permissible).
Open questions to the group:
- Which consumer-accessible app achieves sub-500 ms median alert latency on NBBO changes without relying on client-side foreground execution?
- Any platforms exposing a rule engine for alerts (e.g., boolean logic across price, volume ROC, and imbalance) with server-side evaluation?
- Reliable handling of auction events (open/close) and halts, including pre-open imbalance alerts?
- Concrete privacy posture differences you’ve observed between leading apps (e.g., trackers, PII leakage, or data sharing toggles that actually work)?
- For non-pro users, which data entitlements materially limit alert precision, and are there workarounds within exchange policies?
Looking for real measurements, not marketing claims. If you have logs or anonymized summaries, even better.