word-aligner

Word Aligner

Word Aligner generates shareable interactive diagrams showing which words in one text correspond to which words in another. Words are connected by colored arcs; tokens sharing a connection group (many-to-one or one-to-many) get the same color automatically.

API endpoint: POST https://aligner.tinygods.dev/api/align
Returns: { "url": "https://aligner.tinygods.dev/?data=..." } — give this URL to the user.

Minimal request

{
  "lines": ["I sleep", "Я сплю"],
  "alignments": [[0, 0, 1, 0], [0, 1, 1, 1]]
}

alignments entries are [lineA, wordA, lineB, wordB]: word wordA of line lineA links to word wordB of line lineB. All indices are 0-based, and the two lines must be vertically adjacent (|lineA − lineB| = 1).

Workflow

1. Translate the phrase yourself (or use the user's existing translation).
2. Identify which source words correspond to which target words.
3. Call the API.
4. Return the url to the user with a brief explanation.

Word index counting (read carefully — this is the #1 source of mistakes)

Word indices are token positions, so you must tokenize a line exactly the way the service does before assigning indices:

1. Whitespace always splits. "I have been going" → I[0] have[1] been[2] going[3].
2. The tokenSplitChars characters also split, and are then removed from the output. The default set is .-|. So "go.PST.IPFV" becomes three separate tokens go PST IPFV and the dots disappear from the rendered diagram. This is usually not what you want for Leipzig glosses — see the gloss pattern below, which sets tokenSplitChars to "-|" to keep the dots.
3. Punctuation stays attached by default. "Hello, world!" → Hello,[0] world![1] (the comma and exclamation mark are part of the tokens, not separate).
4. The merge char + joins parts into one token rendered with a space: "is+playing" is a single token (index counts as one word) that displays as is playing.
5. RTL lines: word 0 is the logically first word (the rightmost one on screen for Hebrew/Arabic). Index in reading order, not visual order.