Short answer: For in-depth drone flight log analysis, the best all-round tool is PlotJuggler: it opens PX4 ULog files locally, plots every logged topic by drag-and-drop, and supports custom transforms — which is why the official PX4 documentation itself recommends PlotJuggler for log analysis and carries a dedicated guide for it. For a fast, no-install first look at a PX4 log, PX4 Flight Review (logs.px4.io) is the official online analyser — you upload a ULog and receive plots by email link. UAVLogViewer is a web-based ULog viewer used by the community. On the ArduPilot side, Mission Planner — the ArduPilot ground station — is the familiar home for reviewing ArduPilot logs. Which one is “best” depends on whether you fly PX4 or ArduPilot, and on whether a quick check or a deep investigation is the job. Part of our Alternatives & Comparisons hub.
The evidence table
| Tool | Form | Log scope | Best at | Limits (stated honestly) |
|---|---|---|---|---|
| PlotJuggler | Free offline desktop app (MPL-2.0) | PX4 ULog natively; also CSV, MCAP, ROS bags and more | Deep analysis: every uORB topic plottable, layouts, time offsets, built-in transforms, Lua (and PJ4 Python) custom series — e.g. deriving attitude from quaternions, as PX4’s own guide demonstrates | A desktop install; very large ULogs (over ~2 GB) are a known hard case for loading |
| PX4 Flight Review | Official online service (logs.px4.io) | ULog only | Zero-install quick review: upload a log, get an emailed link to plots including PID and vibration analysis | ULog only by design — no ROS bags, no CSV, no streaming; your log is uploaded to a third-party service |
| UAVLogViewer | Web-based viewer | ULog | A browser-based way to open a ULog without installing a desktop application, used by the PX4/ArduPilot community | We describe it only at this level deliberately: we have not verified a detailed feature list from a primary source |
| Mission Planner | ArduPilot ground station (desktop) | ArduPilot logs | The native home for ArduPilot users: the ground station the ecosystem already uses, with log review as part of that workflow | An ArduPilot-side tool, not a general time-series analyser; not the tool for ROS bags or cross-format work |
Why PX4’s own recommendation carries weight
Vendor-neutral documentation rarely names a favourite, which is what makes the PX4 case notable. The official PX4 documentation does not merely list PlotJuggler — it publishes a full “Log Analysis using PlotJuggler” guide covering installation, the ULog workflow, and a Lua custom series that converts quaternions into roll, pitch and yaw. The same documentation ecosystem points quick-look users at Flight Review and deep-analysis users at PlotJuggler, which is exactly the division of labour this roundup recommends. The reasoning is structural: a ULog contains far more than the handful of signals a summary plot shows — every uORB topic the flight controller logged — and investigating a vibration, a tuning regression or a one-off anomaly means plotting the topic nobody thought to chart, overlaying it against the event, and computing the derived series the log does not contain. A desktop analysis tool with transforms and layouts is shaped for that; an upload-and-summary service, by design, is not.
Pick by job
| The job | Pick | Why |
|---|---|---|
| “Did that flight look normal?” — a two-minute sanity check | PX4 Flight Review | No install, official, and the emailed plots answer exactly that question |
| Tuning, vibration hunting, or investigating an anomaly in a PX4 log | PlotJuggler | Every topic available, custom transforms, layouts you reuse across flights; start with our tutorials and the Download page |
| Opening a ULog in a browser, on a machine you cannot install on | UAVLogViewer | Web-based ULog viewing is its reason to exist |
| Reviewing ArduPilot logs inside the ground-station workflow you already use | Mission Planner | It is the ArduPilot ecosystem’s own tool, framed for that ecosystem |
| Analysing many flights over weeks to spot longitudinal change | PlotJuggler — with the workflow discipline in our alternatives guide | Layouts applied consistently across logs are the manual version of this; the platform-scale version is assessed honestly in PlotJuggler Alternatives |
Two practical notes. First, privacy and logistics cut differently per tool: Flight Review and web viewers ask you to upload or open logs outside your machine, while PlotJuggler analyses the file where it sits — for proprietary airframes or client data, that distinction can decide the question before features do. Second, if your flying also involves ROS — companion computers, offboard control, logged rosbag2 recordings alongside the ULog — PlotJuggler is the only tool in this table that opens both worlds in one window, which is why it also anchors our ROS 2 visualization roundup. Finally, whichever tool you choose, keep the original log file untouched and work on copies — every workflow in this table rewards an analyst whose raw evidence stays pristine, and storage is cheaper than a flight you cannot repeat.
Keep learning
Flight logs accumulate fast and are painful to lose or to share by email attachment. If you keep a backed-up, shareable archive of your ULog files, one practical option is pCloud
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