LAGSCOPEthe connection test built for gamers
Latency — last 3 minutesauto · grows with data latency baseline spike threshold lagspike no data
Ready for ✓ good ⚠ borderline ✗ risky
per-game readiness from your measured baseline, jitter & loss ⓘ
Lagspike & outage log
Do something with it
Join the Discordverdicts, outage alerts, help — discord.gg/C28Kq3qm7e→Lagspikes per hour — last 12 h
Packet loss — last 10 min failed-probe ratio
30 s buckets · GAME TRAFFIC = true UDP loss · STANDARD = failed-probe ratio (TCP hides some loss)
Last 24 hours minor major severe / outage
spot patterns — e.g. congestion every evening
Bufferbloat stress test
8 s of download saturation while latency probes keep running; compares your latency idle vs under load. A big jump means your router queues packets — lag whenever someone downloads or streams. Uses ~10–30 MB.
Outages
| Start | Duration | Status |
|---|---|---|
| no outages — connection has been up | ||
ISP evidence
Everything recorded — lagspikes, outages, jitter, loss, uptime — bundled as proof for your ISP. Print-friendly report in plain language; the CSV has every event with ISO timestamps.
Settings
What am I looking at?
Game traffic — header toggle: real UDP packets (WebRTC, 128 bytes at 30 Hz, no retransmission) instead of HTTP/TCP. This is how games actually talk, so latency and loss match in-game reality. Falls back to HTTP automatically if UDP can't get through.
Baseline — your normal latency (rolling median). Spikes are measured against it — the monitor adapts to your line.
Jitter — how much latency jumps between probes. Under 5 ms rock solid; 15–20+ ms stutters games and robotizes voice even at a good average ping.
Packet loss — probes that never came back. Above ~1% is noticeable in games (rubber-banding, teleporting).
Lagspike — latency above your baseline, sustained ≥0.5 s — shorter micro-bursts are absorbed by game netcode and never counted. Severity: minor (small jump), major (+60 ms), severe (+150 ms or sustained loss); bands scale up on high-baseline lines (satellite, fixed wireless). Duration counts only time actually above threshold — a one-probe blip shows as <1 s.
Link test — small periodic check (a few dozen KB) that the path is alive and consistent. Not a speed test — use a real one for that.
Last 24 hours — hourly rollup of spikes by severity + outage markers, so patterns (congestion every evening) jump out. Hover a bar for details.
Outages — declared only after 2+ consecutive failed probes spanning 3+ s, so one dropped packet never counts. If all 3 LagScope nodes are unreachable we say so — that's your line or DNS, not us.
Discord alerts — paste a webhook URL in Settings: severe-spike and outage alerts in your own Discord channel.
Note — measurements run from this browser to your fastest LagScope node (US, EU or BR, picked by measured latency at page load — the right end of the header path). They describe that path — a good real-world proxy for game-server traffic.
Visible tab only — LagScope measures only while this tab is visible: browsers freeze hidden tabs (timers ~1 Hz, batched callbacks), so anything "measured" there would be fake lagspikes. While hidden, measurement pauses and the chart shows an honest gap; timers count visible time only. For long sessions keep the tab visible or install LagScope as an app (PWA).
Speed test says 500 Mbps but your game still lags?
Bandwidth and stability are two different things. A speed test measures how much data your line can move in a few seconds — the size of the pipe. Online games don't need a big pipe; they need a steady one. A game sends small updates dozens of times per second, and what ruins your match is not slow throughput but moments where those updates arrive late or not at all:
- Lagspikes — latency suddenly jumps from 25 ms to 300+ ms for a second or two. You teleport, shots don't register, then everything "catches up".
- Jitter — latency that won't sit still. Above ~15–20 ms of jitter, movement and voice feel choppy even at a low average ping.
- Packet loss — updates that never arrive at all. Even 1% causes rubber-banding.
- Bufferbloat — your connection is fine until someone starts a download or stream, then latency explodes because your router queues packets. Run the stress test above to check yours.
Ordinary speed tests average all of this away. LagScope probes your connection every 500 ms and logs every spike, dropout and outage with an exact timestamp — so you can see the problems your speed test hides, and prove when they happen.
How to prove internet problems to your ISP
"Looks fine on our end" is what every gamer hears. ISPs check the signal at your modem at one moment in time — they never see the 30-second outage you had at 21:40 last night. The way to win that conversation is with timestamped evidence:
- Leave LagScope running in a browser tab while you play or work. It records every lagspike (with severity) and every confirmed outage (2+ failed probes spanning 3+ seconds), plus continuous jitter, packet loss and uptime figures.
- When problems happen, note the time — the log will have the exact start, duration and peak latency of each event.
- Click "Download ISP evidence" to generate a print-friendly report: measurement period, baseline/p95/p99 latency, average and peak jitter, packet loss %, uptime %, and full lagspike and outage logs — with a plain-English summary you can paste into an email.
- Attach the CSV export if support asks for raw data — every event with ISO timestamps.
A report showing "23 lagspikes (4 severe) and 2 outages totalling 3 min 12 s of downtime between 14:02 and 18:47" is much harder to dismiss than "my game lags". Run it during the hours you usually play — patterns like congestion every evening are exactly what ISPs can act on.
FAQ
How is LagScope different from a speed test?
Speed tests (Ookla, fast.com) measure capacity — average bandwidth and idle ping over TCP to a nearby server. Games die from short instability: lagspikes, jitter, packet loss, bufferbloat. LagScope measures consistency the way a game feels it — real unreliable UDP at 30 Hz in GAME TRAFFIC mode, spikes sustained ≥500 ms, true packet loss, and a per-game READY FOR verdict. Independent: no VPN, router, or ISP service sold.
What is a lagspike?
A short moment where latency jumps far above normal — 25 ms to 300 ms for a second or two. Even brief spikes cause missed shots, freezes and rubber-banding, and ordinary speed tests never see them.
Why doesn't my speed test show lagspikes or packet loss?
Speed tests average a few seconds of maximum bandwidth. Lagspikes, jitter and short dropouts live between those averages — 500 Mbps can still stutter every few seconds. LagScope probes every 500 ms and records each event with an exact timestamp.
What jitter is bad for gaming?
Jitter is the variation between consecutive latency measurements. Under 5 ms excellent, 5–15 ms fine for casual play; consistently above 15–20 ms causes stutter, delayed actions and robotic voice — even at a good average ping.
What is bufferbloat?
Excessive queuing in your router or modem: under load, packets pile up in a buffer and latency balloons. A top cause of lag that only appears while the connection is busy. The stress test above measures exactly this — latency idle vs under load.
Does LagScope work in a background tab?
No — by design. Browsers freeze or throttle hidden tabs, so anything measured there would be a browser artifact fabricating lagspikes that never happened. LagScope pauses while hidden and resumes cleanly on return; the chart shows an honest gap and timers count visible time only. For long sessions keep the tab visible or install LagScope as an app (PWA).
Does LagScope use much data?
Roughly a voice call. Not a download.
Where is my measurement data stored?
Everything stays in your browser — events, outages and settings live in localStorage; reports and CSV are generated locally. Two optional exceptions, both off by default: a Discord webhook you paste yourself (alert posts), and "Contribute anonymous stats" (ISP name, country and metrics — never your IP — to the public ISP leaderboard).
Can I get alerted when my connection drops?
Yes — paste a Discord webhook URL in Settings and LagScope posts to that channel on severe lagspikes and outage start/end (with the downtime). Fire-and-forget: a failing webhook never interferes with measurement.
What is GAME TRAFFIC mode?
Standard mode uses small HTTP requests over TCP — and TCP silently retransmits lost packets, hiding true loss and stretching spikes. Real games send small UDP packets 20–60 times a second with no retransmission. GAME TRAFFIC mode reproduces that: a WebRTC DataChannel in unreliable/unordered mode, 128-byte packets at 30 Hz — genuine UDP on the wire. You get true packet loss and latency that matches in-game experience. If UDP can't get through, LagScope falls back to HTTP and tells you.
What do "YOU" and "SERVER" mean in the header?
Every measurement is a path between two points: your connection and the LagScope node. The header shows both ends — your ISP and city (looked up from your public IP, never stored) on the left, the node your probes go to on the right. A great result means that path is healthy — a good proxy for nearby game servers, though routes to other destinations can differ.
Which server does LagScope measure to?
Your fastest node (US, EU or BR), chosen by real measured latency at page load — all nodes are probed and the lowest median RTT wins, for HTTP and GAME TRAFFIC (WebRTC/UDP) alike. Re-chosen every load because routing changes; pin a node in Settings under "Measurement node".
Which ISP is best for gaming?
Check the LagScope leaderboard — ISPs ranked by real, anonymized measurements (readiness score, latency, jitter, packet loss, lagspikes per hour) from opted-in users, grouped by ISP and country. No IPs or personal data collected.