01
Plan the week
Draw the route. Block out the weeks. Build the intervals.
Public TestFlight beta
Plan the route. Plan the fuel.Let the run log itself.
An iPhone training app for trail and ultra runners. Map the climb, dial in the fuelling, then go and run it. The checkmarks land on their own.
Device
iPhone · iOS 26+
Activity source
Garmin · Strava
Recording
Not on your phone
Stage
TestFlight beta
How it works
Most training apps stop at the plan. TrailForge closes the loop.
02
Fuel the session
Carbs, fluid and salt sized to this run and this forecast — not a generic number.
03
Run it on your watch
Send it to your Garmin and go. Nothing to start, nothing to remember.
04
It ticks itself off
The run finds its session on its own. You don't even open the app.
Fuelling
Nobody bonks on purpose.
Attach a fuel plan to any session and TrailForge reads the whole picture — how long you'll be out, how hard you're going, how warm it'll be at the start line, how much you weigh — then hands you carbs, fluid and salt per hour, with the reasoning in one plain sentence. Conservative, Balanced or Aggressive to start; change anything you like.
- It pushes back when it matters. Past 60 g an hour your gut can only take so much of one sugar — TrailForge says so, and tells you to add a second. It catches salt that's too thin for the fluid you're carrying, and caffeine that'll still be with you at bedtime.
- Plan the vest, not a spreadsheet. Pick the gels, mixes and chews you're actually carrying — from the catalogue or your own — and TrailForge spaces them into a schedule you can follow on the move.
- Then it learns your gut. Log what you actually took and how you actually felt. Two good runs in, it stops quoting the textbook and starts quoting you — held below the intake that's caused you trouble before.
Fuel plan · 2:40 h
Example
Carbs75g/hr
Fluid575ml/hr
Sodium800mg/hr
82%
Carb coverage
164 g planned across five windows, against a 200 g target.
“2:40 h at moderate effort → 55–90 g/hr is the evidence-backed range.” Above 60 g/hr, add a second carb type.
Plan & actual
The run you just did finds the session you planned.
Finish your run. By the time you've stopped stretching it's already matched to the session it was meant to be — on when you went, how far you got, and where you started from. One run, one session. It won't double-count to flatter your week.
- Your phone stays in your pocket. The checkmark lands and the widget moves on to what's next before you've even unlocked the screen.
- Progress you can trust. A week is done when the sessions are done — not when the calendar says so.
- Your week, on the home screen. Distance against target, where the effort actually went, and what's next — with its weather and the best hour to head out. No tap required.
This week · Specific
Example
Threshold 5×6′
Recovery
Long run
SunEasy + strides
Three of four linked automatically from Garmin — matched on date, distance and start location. Nothing was tapped.
Routes & weather
Draw the line, then see the day it's going to be.
Tap out a route and it snaps to real trails and paths. The climbing you see is the climbing you'll do — read straight off the terrain, with no phantom vert padding the number. Drag a finger along the profile and watch the hill move under it.
- The best hour to leave. Tell it the temperature and sky you like running in and how far you're willing to shift, and it reads the whole day to find your window.
- Weather where you'll actually be. Temperature, rain, wind and gusts projected along the route at your pace — not just what it's doing at the trailhead.
- It knows when the light goes. The dark stretch is shaded straight onto your elevation profile, so you pack the headlamp before you need it, not after.
Worth knowing: there's no GPX import yet. Routes are drawn here or arrive from Strava, and they push out to Garmin as courses.
Bymarka loop
Best start 07:00
Distance18.4km
Ascent620m
Est. time2:12
Sunset 21:14 — the last 3 km are in the dark. Pack a headlamp.
Training plans
Structure, down to the interval.
One week, or a full fifty-two. Mark each one Base, Intensity, Recovery, Taper or Specific, and watch the distance and vert you planned sit right next to what you've actually banked.
- As loose or as precise as you want. Just a distance to cover — or a full session with warm-up, repeats, rests and cool-down, dragged into whatever order you want them.
- A target on every step. Pace, heart rate or cadence, set as a range you can actually hold. Ending on the effort instead of a rest is one tap.
- Write it once, run it all season. Save a session to your library, drop it into any week, and send it straight to your Garmin calendar.
Kullamannen 100M
8 weeks
Week 1Base
Week 2Base
Week 3Recovery
Week 4Specific
Analysis
Pace lies on a mountain.
A brutal climb and a bad day look identical in raw minutes per kilometre. TrailForge puts grade-adjusted pace next to the real number, so the effort you actually put in is the one you get credit for.
- Splits that account for the hill. Every kilometre with its climb, its descent, its heart rate — and what your pace would have been on the flat.
- Zones with names, not numbers. Tap through Recovery, Endurance, Tempo, Threshold and Max and see where the session really sat — then break it down lap by lap.
- Read a whole week at a glance. Every run in the list carries its map and a colour bar of the effort, so a block of training tells its story before you open anything.
Trail run · 21.6 km
Example
Avg pace5:42/km
Avg GAP5:11/km
Avg HR148bpm
Time in zones
GAP is 31 s/km quicker than raw pace here — the climb was doing the work.
Integrations
Works with the watch you already own.
Garmin
Two-wayEverything you record lands here on its own — no uploads, no lost sessions. And everything you plan here goes straight back out to the watch.
- Routes go out as Garmin Connect courses
- Planned workouts land on your Garmin calendar
- Activities, heart rate, routes and elevation come in
Strava
ImportBring across the runs you already have, so your log starts full instead of empty.
- Rides and runs
- Heart-rate data
- Routes and elevation
TrailForge doesn't record your runs — your watch does. Connect both Garmin and Strava and the same run can arrive twice; the app tells you when that's the case. Disconnecting revokes access at the provider itself, not just on your phone.
And the rest
The details you notice in week three.
Search that takes a number
Find it by name — or forget the name. “Everything over 20 km” is a valid search. So is everything with more than 1 000 m of climbing.
Sessions keep their own clock
Book 9:00 for a race in Chamonix and it means 9:00 in Chamonix. You'll always know which clock you're reading.
Set up in five slides
Your details, your zones, the weather you like running in, your watch, notifications. Skip whatever you want and come back to it later.
Start as a guest
The whole app, no account, no email. Sign in with Apple or Google whenever you feel like it and everything follows you across.
Your units, everywhere
Kilometres or miles — or just follow the phone. Set it once and every chart, split and plan falls in line. Widget included.
Your season in one place
Season totals on your profile, and stats you can walk back through by week, month or year to see how the shape of your training changed.
Questions
Straight answers.
Does it record my runs?
No. TrailForge never uses your phone's GPS to record. It reads finished activities from Garmin or Strava, so you run with the watch you already own. Without one of those connected you can still build plans, draw routes and write fuel strategies — but nothing will fill itself in afterwards.
What do I need?
An iPhone on iOS 26 or later, and the free TestFlight app. The interface is dark only, by design. There's no iPad, Mac, Android or web version, and none is in testing.
Do I need an account?
No. Continue as a guest and you get the whole app. Sign in with Apple or Google later and your guest data carries over on the same account — nothing is lost. There's no email-and-password option.
Does anything sync back to my watch?
With Garmin, yes, and it's opt-in. Turn on route sync and your routes appear in Garmin Connect as courses; turn on workout sync and planned sessions land on your Garmin calendar. You can also push a single route or workout on demand without turning on either. Strava is import-only.
Can I import a GPX file?
Not today. Routes are drawn in the app or come in from Strava, and they can be pushed out to Garmin Connect as courses. There's no file import or export yet.
Is the fuelling advice medical advice?
No. It follows mainstream sports-nutrition consensus — roughly 30–60 g/hr for one to two and a half hours, 60–90 g/hr beyond that, and a second carb type above about 60 g/hr — and it flags patterns worth a second look, like a lot of fluid with very little sodium, or caffeine outside 3–6 mg/kg. Guidance, not a prescription.
What happens to my data?
There are no analytics, crash-reporting or advertising SDKs in the app — none. Your Garmin and Strava access tokens are held encrypted on the server, never on your athlete profile, and disconnecting a provider revokes the grant at the provider itself. The detail is in the privacy policy.
It's a beta — what should I expect?
Rough edges, and builds that expire 90 days after upload — that's TestFlight's rule rather than ours. Everything described on this page works today; anything you don't see described here doesn't exist yet. Feedback goes straight to the developer through TestFlight.
The beta is open.
TrailForge is pre-release and moving fast. If you run long, plan your own training and have opinions about fuelling, this is a good moment to get in.
Join the TestFlight beta