diff --git a/src/http/help.zig b/src/http/help.zig
index db56061..c5b9b20 100644
--- a/src/http/help.zig
+++ b/src/http/help.zig
@@ -44,6 +44,37 @@ pub const help_page =
     \\    Q                       # superquiet version (no "Weather report", no city name)
     \\    T                       # switch terminal sequences off (no colors)
     \\
+    \\Output formats:
+    \\
+    \\    format=1                # one-line: "London: ⛅️ +7°C"
+    \\    format=2                # one-line with wind: "London: ⛅️ +7°C 🌬️↗11km/h"
+    \\    format=3                # one-line detailed: "London: ⛅️ +7°C 🌬️↗11km/h 💧65%"
+    \\    format=4                # one-line full: "London: ⛅️ +7°C 🌬️↗11km/h 💧65% ☀️06:45-16:32"
+    \\    format=j1               # JSON output
+    \\    format=v2               # * data-rich experimental format
+    \\    format=p1               # * Prometheus metrics format
+    \\    format=%l:+%c+%t        # custom format (see format codes below)
+    \\
+    \\Custom format codes:
+    \\
+    \\    %c                      # weather condition emoji
+    \\    %C                      # weather condition text
+    \\    %h                      # humidity
+    \\    %t                      # temperature (actual)
+    \\    %f                      # temperature (feels like)
+    \\    %w                      # wind
+    \\    %l                      # location
+    \\    %m                      # * moon phase emoji
+    \\    %M                      # * moon day
+    \\    %p                      # precipitation (mm)
+    \\    %o                      # probability of precipitation
+    \\    %P                      # pressure (hPa)
+    \\    %D                      # * dawn time
+    \\    %S                      # * sunrise time
+    \\    %z                      # * zenith time
+    \\    %s                      # * sunset time
+    \\    %d                      # * dusk time
+    \\
     \\PNG options:
     \\
     \\    /paris.png              # generate a PNG file