Zerdly

Word Ladder

Turn one word into another one letter at a time, with every step a real word. Every pair is checked to be reachable before you see it, and par is a measured shortest route rather than an estimate.

Building a ladder…

How to play

Type the whole next word and press Enter. Each rung of the ladder marks the letter that changed, so you can read your route back at a glance.

Backspace on an empty box takes the last word off the ladder. Undo is always available and never costs anything.

Rules and controls — Zerdly's preset

The five rules of the game:

  1. The start and target words are the same length.
  2. Change exactly one letter per step, in place — nothing is added, removed or moved.
  3. Every word you make must be in the word list.
  4. Changing a letter to the same letter is not a step and is refused.
  5. You finish when you reach the target word.

And two house rules, which are Zerdly's choices rather than rules of the game:

  • A word already on your ladder cannot be used again. Nothing in the five rules forbids it, and it can never help — going back to a word means every step since was wasted. Undo is the honest way back.
  • Shortest Path refuses the step past par. In that preset only, par stops being advice and becomes a limit. Every other preset lets you wander as far as you like.

Why the word list is small on purpose

This game does not use the whole dictionary. It uses roughly the commonest few thousand words, and a tighter slice still for the three-letter preset.

That is not us being stingy, it is the only way par can mean anything. Across the full word list, the shortest ladder between two perfectly ordinary words almost always runs through a word nobody has heard of — so par would be exactly right and completely unreachable. Trimming the list keeps every rung a word you know, and it is why the three-letter preset has the tightest list of all: short words have so many neighbours that a four-step ladder reaches the obscure end of the dictionary almost immediately.

Presets

  • Three-letter Warm-up — Four steps between two three-letter words. Every word here is one of the 4,500 commonest in the list, because short words run out of ordinary company fast.
  • Four-letter Ladder — Five steps between two four-letter words, with room to wander. The broadest, friendliest version — most four-letter words have seven neighbours, so there is nearly always a way on.
  • Five-letter Climb — Six steps between two five-letter words. A different feel entirely: five-letter words average under three neighbours, so this is a corridor rather than a thicket, and the hard part is finding any way on at all.
  • Shortest Path — The same four-letter ladders, with one rule changed: you get exactly five steps and no more. A wrong turn is not a detour, it is a dead end — so undo it and think again.
  • Daily Ladder — One ladder a day, the same for everybody, built from the date. Four letters, five steps, no step limit.

Tips

  • Work from both ends. Ask what could come before the target as well as what comes after your current word — the middle is usually where the route is hiding.
  • Change the vowel first. Vowels have far more one-letter neighbours than consonants, so swapping one is the cheapest way to find out whether a route exists at all.
  • Watch the endings. Words that differ only in a final S, D or R are neighbours, and they are the easiest steps to overlook because they barely feel like different words.
  • In Shortest Path, undo early. The moment a step feels like a detour it probably is one, and you cannot spend your way out of it later.
  • A five-letter ladder is not a bigger four-letter one. With under three neighbours per word, the question stops being which way and becomes is there a way — so try every letter position rather than guessing.

Leaving in the middle of a ladder

There is no clock on this game, so nothing is lost by stopping. Your ladder and the hints you have spent are restored exactly as you left them.

Every saved word is re-checked against the rules as it is restored, rather than trusted. If a saved ladder no longer makes sense, the game hands you back the starting word instead of a position you were never actually in.

Privacy and local play

Everything runs in your browser. Your current ladder, your settings, your best scores and the pairs you have seen recently are kept on this device only, and the button under the game clears them without touching any other Zerdly tool. No account, no sign-in, and nothing about your play leaves the machine you are on.

Questions

What exactly counts as a step?
Changing exactly one letter, in place. The words are always the same length: you cannot add a letter, remove one, or move them around. Changing a letter to the same letter is not a step either — nothing has changed.
I typed a real word and it was refused. Is the game broken?
No — the word list is deliberately small, roughly the commonest few thousand words, and tighter still in the three-letter preset. Over a full dictionary the shortest route between two ordinary words nearly always runs through something nobody has heard of, which would make par technically correct and completely unreachable. Keeping the list small is what keeps every step a word you actually know.
Can I go back to a word I have already used?
No, and that is Zerdly's house rule rather than one of the five. Revisiting a word means every step since it was wasted, so it can never help — and Undo does the same job honestly. Undo is always available and costs nothing.
Is par really the shortest possible ladder?
Yes. Every puzzle is built by picking a starting word, searching the entire word list outwards from it, and then choosing a target that sits at exactly the wanted distance. Par is that distance, measured, so the pair is guaranteed to be connected and the number is guaranteed to be right.
Is there only one right answer?
Usually not. There are often several ladders of the same shortest length, and any of them is an equally good answer. When a round ends you are shown one of them, described as one shortest ladder rather than the solution.
How is Shortest Path different from the other presets?
It changes a rule rather than a number. You get exactly par steps and the game refuses the step that would take you past it, so a wrong turn is a dead end instead of a detour. You can strand yourself at par without arriving — that is the challenge, and Undo is how you get out.
Are three-letter ladders the easy ones?
Not in the way you would expect. Three-letter words have about thirteen neighbours each, so there is nearly always somewhere to go and the difficulty is choosing; five-letter words have under three neighbours, so the difficulty is finding any way on at all. They are different problems, not the same problem at two sizes.
How does the hint work, and what does it cost?
It takes one step for you along a shortest route from where you are standing — not from where you started, so it stays correct however far you have wandered. It never names a word the rules would then refuse. Each hint costs 15 points.
How is a ladder scored?
A finished ladder is worth 10 points for each par step, so a harder ladder is worth more. Every step past par costs 5 and every hint costs 15. The total never goes below zero, and a ladder you did not finish scores nothing.
What happens if I close the tab in the middle?
Nothing is lost. There is no clock on this game, so your ladder and the hints you have spent come back exactly as you left them. Every word is re-checked against the rules as it is restored, so a saved ladder can never put you in a position you were not actually in.
Where does the word list come from?
It is the same 28,000-word common English list Zerdly's Word Scramble uses, built from a public-domain word list and ranked for commonness against a freely licensed frequency list. This game then uses only the most common part of it. Nothing was purchased and nothing was scraped.
Is anything sent to a server?
No. The word list, the search and your progress all run in your browser. There is no account, and clearing this game's data leaves every other Zerdly tool untouched.

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