Mob Hop

Mobs stop giving up at knee-high obstacles. Vanilla will not path through a fence, wall, or closed gate — or across even a one-block gap — so a zombie that can see you just stands and swings at the air. MobHop gives every ground PathfinderMob one honest, survival-weight hop: if the obstacle is short enough (or the gap narrow enough), there is room above, and a safe landing on the other side, the mob clears it.

This is not a parkour mod. No climbing, no wall-running, and no ability unlocked by config: hops are capped in code at three blocks of height and two of gap, and ship at 1.5 and 1 — a vanilla fence, and a single empty column.

Install on the server (and in singleplayer). Clients do not need the mod for mobs to hop, but the jar declares both sides — keep it on both if your pack checks.

Dependencies: Fabric & NeoForge require Architectury API (and Fabric API on Fabric). Forge requires no additional dependencies.

Free to use in any modpack — public or private, no permission needed.

What it does

• Every PathfinderMob — zombies, skeletons, creepers, spiders, illagers, golems, villagers, animals, and modded mobs that extend the same class. Flyers, swimmers, slimes, and shulkers are left alone.
• Fences, walls, gates, and ledges — anything between minObstacleHeight and maxHopHeight of collision; modded fences and walls work without a whitelist.
• One-block gaps — a single empty column between two surfaces is hopped by default (level, up, or down). Wider gaps stay off unless you raise maxGapWidth.
• Measured jumps — landing distance and air time are worked out before takeoff; hops that would not make it are refused.
• Safe landings — no lava/fire/hazards, no pit it cannot climb out of, no ceiling clip, no ledge too narrow for the body, no unloaded chunks at the border.
• Datapack tags — #mobhop:can_hop, #mobhop:cannot_hop, and #mobhop:hazards merge across packs the normal way.
• Live config — save config/mobhop.json and changes apply within a few seconds; no restart and no /reload.

Configuration

config/mobhop.json is written on first launch (every key is commented in the file). A bad parse renames the file to mobhop.json.bak and restores defaults instead of taking the server down.

Defaults that matter most:

• maxHopHeight 1.5 — tallest obstacle (vanilla fence / wall / closed gate); hard ceiling 3.0
• minObstacleHeight 0.6 — at or below this, vanilla step-up handles it
• maxGapWidth 1.0 — widest air run hopped (0.0 = obstacles only; hard ceiling 2.0)
• maxDropHeight 3.0 — deepest accepted landing below the obstacle top
• onlyWhenChasing false — set true so only mobs with an attack target hop (keeps livestock in pens)
• restrictToCanHopTag false — set true for an allow-list via #mobhop:can_hop (shipped empty)
• refuseHazardousLanding / requireSolidLanding — both true by default
• checkIntervalTicks 4 / hopCooldownTicks 20 / reloadCheckSeconds 5 — performance and live-reload dials

Details

• Narrow who hops with #mobhop:cannot_hop (e.g. cows and sheep) or turn on onlyWhenChasing.
• Tag folder name: entity_types / blocks on 1.19.2–1.20.1; entity_type / block on 1.21+.
• Not a pathfinder rewrite — each hop is one local decision. No multi-fence parkour routes, no hopping out of a pen just because a fence is there (something on the far side has to be pulling the mob).
• Wide mobs need wide landings; a ravager or iron golem will not hop onto a one-block ledge.

Feedback

Please report any bugs, errors, or feature suggestions on Discord: https://discord.gg/HTkn94BXmA

More mods by Nikrecs: PathSpeed! · Rope

My other mods that I recommend.