This addon does more than the name suggests. it gives you inventory save/load, and it includes detector tags, scoreboard trackers, and custom commands aimed at command creators.

Only want one feature?  That's fine — just ignore the rest.  Nothing here will interfere with normal gameplay if you don't use it.

btw You can store up to 25 inventory saves. Once you hit the cap, new saves are rejected until you delete some.

/isal:invlist and /isal:invdelete will help you clean up inventory saves you don't need.

if you need to delete all inventory use /isal:invdeleteall.

ADDON REFERENCE

Custom Commands (/)

/isal:inv <target> save <name> — save a player's inventory (+ armor + offhand)
/isal:inv <target> load <name> — restore a saved inventory
/isal:invlist — list all saved inventory names
/isal:invdelete <name> — delete one save by name
/isal:invdeleteall — delete all saves

(save/load have auto-complete; max 25 saves)

Tags that triggers behaviors

Drop items

dmh — drop main-hand item
dhb — drop hotbar
dfi — drop full inventory (+ armor + offhand)
d_<namespace>:<item>_<count> — drop a specific item and amount

Shuffle inventory

shb — shuffle hotbar
sfi — shuffle full inventory

Item cooldown

itemcoold_<ticks> — set/freeze held item's cooldown to <ticks>
noitemcoold / nicd — cooldown-clear tags

Knockback

kb_<x>_<y>_<z> — apply knockback (auto-clears)
kb_<x>_<y>_<z>_look — apply knockback relative to view direction
kb_resis_1 — 75% knockback kept
kb_resis_2 — 50% kept
kb_resis_3 — 25% kept
kb_resis_4 — full knockback immunity

Double sneak

d_c — pulses on double-sneak (auto-removed after 2 ticks)
d_c_h — held while the second sneak is held

Tags — ADDED automatically

Player state (live): 

climbing — a latters or vines, 
emoting,
falling, 
flying — creative mode flight, 
gliding — flying with a elytra, 
inwater, 
jumping, 
onground, 
sleeping — in a bed, 
sprinting, 
swimming, 
sneaking

Effect tags: 

effect_<name>_<level> — one per active status effect

Biome tag: 

biome_<name> — current biome (if enabled)

Event tags: 

useitem — right click tag the player with "useitem", 
itemstartUse — start using right click, 
itemstopUse — stop using right click, 
buttonpush, 
changeslot, 
playerjoin, 
playerrespawn, 
hasleft, 
hitter — attack a entity
entityHurt — get attack by a entity,
popped_totem

Scoreboards

Hit tracking: 

hitter, 
hitter_2, 
entity_hitter, 
entity_hitter_2, 
player_hitter, 
player_hitter_2, 
hit, 
hit_2

Kills / deaths: 

kills, 
kills_2, 
deaths, 
deaths_2, 
player_kills, 
player_kills_2, 
player_deaths, 
player_deaths_2, 
mob_kills — player kill mobs, 
mob_kills_2 — player kill mobs, 
mob_deaths — player die to a mob, 
mob_deaths_2 — player die to a mob

Per-mob kills: 

kill_<mob> — auto-created per mob type killed

Effects: 

eff_<name> — remaining duration per active effect

TPS:— tick per Second.

tps (whole), 
tps_x10 (×10 for decimals), 
ptps (per-player) — under participant server

Health: 

health — each player's current health

World and player stuff:

day (1 = day, 0 = night), 
weather (2 = thunder 1 = rain, 0 = clear), 
mined (blocks broken), 
ple (blocks placed),