Someone sent you a recording and you don't know how to open it? Your sonar records sonar data and the manufacturer app feels limited? Horizon Sonar is the web viewer for sonar recordings: drag the file onto the browser and see the recording in seconds. No software, no drivers, no install.

Email and password. 30 days free, no card. Plenty of time to open every recording you've saved over the season.
Plug the sonar SD card into your computer, or grab a recording someone sent you on WhatsApp. Drop it on the browser, it uploads.
In seconds the viewer shows depth, fish echoes, GPS trail on the lake map, water temperature and any waypoints you marked.
The full water column with depth gradient. Identify bottom steps, vegetation, thermoclines at a glance.
The boat path on the lake outline. See where you passed each minute and how deep it was at every point.
Each fish arc with depth and estimated size. Filter by threshold, zone or hour.
Water temperature per ping and scrubbable timeline. Jump to any exact moment of the session.
sonar recording is the proprietary binary format used by Horizon sonars. Each file contains a complete sonar session: a sequence of pings with timestamp, GPS, depth, water temperature and detected echoes. Compact format designed for many hours of recording without filling gigabytes.
Fastest way is uploading to Horizon Sonar and viewing in the browser. No software to install, no updates to maintain, no OS lock-in. Works on Windows, Mac, Linux and mobile.
Yes: 30 days free at Horizon Sonar, no card. Upload what you need, view, download, share. €2/month afterwards if you want to keep storing them in the cloud. If you don't continue, you download everything and keep your recording.
The system handles 6-8 hour sessions without issue. Resumable uploads — if the connection drops, the upload resumes where it left off.
Files travel over TLS and are stored on Backblaze B2 with EU servers. Recordings are private by default — only you see them. To share, you generate a specific public link.
Create a free account, upload it, see what your sonar captured. 30 days, no card.