Migrate from dictionaryapi.dev

If your app looks up English words through Free Dictionary API, point the same lookup path at a Vocab Bloom Hub instance. The compatibility adapter returns the familiar JSON array for both v2 and legacy v1. The definitions come from the active dataset of your instance, so changing the URL does not reproduce the upstream dictionary.

Change the base URL

For example, the public project instance answers at https://vocab-bloom-hub.com/api/compat/dictionaryapi/v2/entries/en/hello. If your client stores the full URL, replace its prefix and keep the language and encoded word path segments. The legacy /v1/entries/en/{word} path works too. These are anonymous, read-only requests; no API key is needed. They do not contact dictionaryapi.dev.

const baseUrl = 'https://vocab-bloom-hub.com/api/compat/dictionaryapi';
const word = 'hello';
const entries = await fetch(`${baseUrl}/v2/entries/en/${encodeURIComponent(word)}`).then((r) => r.json());

en and the historical en_US / en_GB aliases are accepted. Other languages are not available through this adapter. It does not accept query parameters, including dataset. Use a PostgreSQL instance with the desired dataset installed, then activate that dataset on its card in the admin UI. Activation changes what all public lookups on the instance serve. On SQLite only the default dataset is available.

Read every dataset in this format

Append /datasets to the compatibility lookup:

curl -fsS 'http://localhost:3240/api/compat/dictionaryapi/v2/entries/en/hello/datasets'
# The legacy v1 format is available too:
curl -fsS 'http://localhost:3240/api/compat/dictionaryapi/v1/entries/en/hello/datasets'

These Vocab Bloom Hub extensions read every installed dataset without activating one. The outer response is { data, meta }. Each data[] group contains its dataset terms (including dataset, title, active, source and licenses), a status, and a response:

• status: 200: response is the same v1 or v2 array the ordinary adapter would return from that dataset, with full vocabBloom provenance.
• status: 404: response is the adapter's { title, message, resolution } missing-word object for that dataset.

The overall HTTP status is 200 even if every dataset misses. meta contains the requested word and language, the number of datasets, and found (datasets with matching entries). Unsupported languages still fail the request with 404; query parameters remain unsupported.

For example, extract the WordNet group's result without changing the active dataset:

curl -fsS 'http://localhost:3240/api/compat/dictionaryapi/v2/entries/en/hello/datasets' \
  | jq '.data[] | select(.dataset == "wordnet") | {status, response}'

Only installed datasets appear; an uninstalled WordNet has no group. On SQLite the answer has the single default dataset. The ordinary lookup URL still returns an array from the active dataset; the /datasets wrapper is an extension for tools that need all datasets. See the complete all-datasets contract.

Check your client before switching

• The adapter returns one array item per entry/part of speech. The number of items and definitions can differ from upstream. The v2 shape uses meanings[]; v1 uses meaning.
• Its vocabBloom fields and sourceUrls describe the actual source. Do not relabel the project dataset or OpenGloss as Wiktionary. Clients that reject unknown fields must allow vocabBloom; preserve the applicable licenses and attribution when redistributing data.
• Missing words and unsupported languages return an upstream-shaped 404. Inflected forms can resolve to a base word. The instance has its own rate limit and cache policy.
• Pronunciations, examples, synonym grouping and word coverage depend on the installed dataset. Compare words important to your app before switching production traffic.

For the complete mapping and HTTP limits, see dictionaryapi.dev compatibility. For dataset installation and activation, see Datasets.

Website comparison snapshots

The website comparison uses saved original-service responses for all nine preset words and supported version/translation options. They are committed with the website and refreshed manually with yarn workspace site comparisons:generate (--missing-only retries missing or failed snapshots). Building, starting and browsing the site never requests the originals. The retrieval date is displayed. A failed refresh retains an older successful snapshot with a warning when available; otherwise the error is shown. Instance datasets are queried live.

Unavailable v1 examples are reconstructed from saved v2 responses using the service’s published transformV2toV1 mapping. The comparison labels them as reconstructed, without a v1 retrieval date or an observed HTTP status. A manual refresh can replace them with actual v1 responses; a failed refresh retains the reconstructed example.