What is KADALTO?
KADALTO is a free set of web tools for cycling files. Your ride file is read and edited in your browser, and an edit makes a new download instead of touching the original. It comes in two parts. Workshop is 18 tools that each do one job. Studio is an editor for making several changes to one ride, with a map, charts, history and a preview before anything applies. The site calls itself an independent project, and a developing one, with a small Demo label beside its logo that it doesn't explain. It names no person or company, and its legal pages date from October 2026. It's available in English, French, German, Dutch, Spanish, Italian and Portuguese, with metric or imperial units.
It works on files, not on your account. There's no Strava login. Its help page has a section on uploading to Strava: download the finished FIT, GPX or TCX file, open Strava's uploader, choose the file, then review and save. On a phone you pick the file using Strava in your browser. Strava's help says it accepts those formats up to 25MB if the file holds actual workout data. KADALTO's help says to use a recorded activity with timestamps and warns that Strava may reject duplicates.
Key Features
Studio
Open one recording and the original, the current ride and any pending preview stay separate. You preview a change, apply it, undo it if you change your mind, then export a checked file. The tools on offer adapt to the file, and KADALTO says Studio doesn't promise that every standalone tool can be chained in every format. With a free account, once you're in Studio, the map offers a ride replay that skips stops, and a 30 or 60 second video, landscape or portrait, to share.
Trim, split and merge
Trim works on FIT and GPX. You can remove one or more sections, including from the middle, keep a single range, or shorten the ends. Closing the gap a cut leaves is a separate setting, because it moves later timestamps earlier. Split makes two files from a FIT activity or a timed GPX track. Merge joins FIT, GPX or TCX parts of one ride, three or more if needed. They have to be the same format with compatible timelines, and it checks every join.
Elevation
For FIT and GPX, match heights to terrain, make a manual correction, or remove elevation altogether, and compare the profiles before you keep anything. KADALTO says terrain heights are estimates that can differ at bridges and tunnels, and that a corrected file isn't guaranteed to show the same climbing on Strava, which may recalculate after import.
Sensor data
Combine sensor data borrows heart rate, power, cadence, temperature, speed or elevation from a second FIT recording of the same ride, say a watch alongside a bike computer. The route, timestamps, distance, laps and device stay with the main file. Where the second recording has no reading, the main file keeps its own, and gaps are never invented. Clean up sensor data handles spikes in power, heart rate or cadence on FIT, and in heart rate or cadence on TCX.
Convert, export and compare
Once you open a file, Convert offers FIT activities to GPX or TCX, GPX tracks to TCX, TCX activities to GPX, a GPX route or track to a FIT course, FIT or TCX courses to GPX, and a coordinate CSV to GPX. Converting to TCX asks you to enter the recorded calorie total. A conversion can lose what the new format can't hold, GPX doesn't carry every FIT field, and KADALTO shows a summary of what's kept before you download. Export gives a readable CSV or JSON, and Compare reports the differences between two files.
Restore a ride ending
For a FIT ride that stopped recording a little early, this adds up to 2% of the recorded distance along the mapped road, so 99.5 km can reach 100 km. New heart rate, power and cadence samples use the file's averages, added time is set to keep average speed close, and elevation, calories and training scores aren't extended. KADALTO labels the addition as estimated and says not to present it as independently recorded. It doesn't guarantee the same distance or average on Strava, which can recalculate them. It needs a free account, takes only single-activity GPS FIT files, and refuses compressed timestamps and files that have already been extended.
The smaller jobs
Adjust ride time shifts every timestamp or sets a new start. Hide start & finish removes points near the ends of a ride. KADALTO says that reduces exposure without guaranteeing anonymity, since a later visit can still show the place. Edit file details changes names, notes and sport. Change recording device edits the FIT manufacturer and model, some of them as a name only. Clean up GPS finds jumps, simplifies a track or removes exact duplicates in GPX. Reverse a route flips a planned GPX. Inspect shows what a file holds, and Process multiple files puts the successes in a ZIP. Once you add files, it says a queue holds up to 20 files and 100 MiB, and the actions are shifting timestamps, exporting JSON or CSV, or converting to a GPX track or TCX activity.
Who It's For
- Riders who left the computer running, in the car or through a long stop
- Anyone whose ride broke into several files after a restart or a flat battery
- Riders who recorded on two devices and want heart rate from a watch in the bike computer's file
- Riders who doubt their climbing figure and want to see the profile against terrain
- People sharing a file who'd rather not show where they start and finish
What it doesn't do
It doesn't connect to Strava. It can't fetch your activities or send a file back, and its merge page says it won't change the original activities there. It also says it can't promise another service will accept a file or show identical statistics.
Not every tool takes every format. Trim and Split don't accept TCX. Clean up GPS is GPX only, which KADALTO says is not a universal FIT GPS repair. Combine sensor data, Restore Ending and Change recording device are FIT only.
Once a file is open, the only FIT output Convert offers from another format is a course, and a course isn't a recorded activity. So a GPX or TCX activity can't become a FIT activity here.
The FAQ says it isn't a universal recovery service for damaged files, so a truncated or unreadable recording may not open at all. Pages are written for cycling, and we found no description of running or other sports. Inside the tools, trimming or merging a FIT file recorded as another sport is refused, and Restore Ending asks for a recorded cycling activity. We found no mobile app. Work in progress sits in browser memory, so it's gone if you close or reload the tab without downloading or saving, unless you've turned on Studio's local recovery, which keeps one ride in that browser for up to seven days.
What leaves my browser?
By the privacy page, the contents of your ride file don't, unless you choose Save. Maps do make requests for the area you're viewing, and terrain correction and 3D replay request height tiles through KADALTO, so those providers see geographic regions. Restore Ending checks fingerprints and distance totals with KADALTO, and once you're in that tool it says the map uses your finish location to find nearby roads; the privacy page doesn't list that road lookup. Analytics stay off until you allow them, and KADALTO says they never include ride files, filenames, coordinates, ride times or sensor readings.
What happens when I save a ride to an account?
The file or Studio project goes to private account storage, including the original recording and your edit history, and stays until you delete it or the account. The operator can see account identity, sign-in activity, file names and storage totals, not recording contents, and a new account's IP address and approximate country are kept for 90 days. Accounts start at 50 projects and 100 MiB in total, with 64 MiB per project. You sign in with Google or a one-time code sent by email. The privacy page says saved files aren't used for advertising or model training.
Why does Restore Ending need an account when other tools don't?
KADALTO uses it to enforce the extension limit. Fingerprints of the recording are worked out on your device and kept as keyed hashes in your account history, with no filenames, route points or sensor readings, so removing a file's metadata doesn't reset that history. The FIT file itself isn't uploaded for this check.
