JS SDK

@form-engine/sdk — framework-agnostic, ESM + UMD, under 3 KB gzipped.

npm install @form-engine/sdk

FormEngineClient

new FormEngineClient(slug: string, options?: { baseUrl?: string })

Method	Does
`.load()`	Fetches the published schema. Returns `{ slug, name, version, schema, maxUploadSizeBytes }`.
`.uploadFile(file, contentType)`	Authorizes an upload, then PUTs the file directly to storage. Returns `{ r2Key, contentType, expiresAt }` — put `r2Key` in your submit data for that image field.
`.submit(data, { draft?, turnstileToken })`	Submits the form. Returns `{ success, submission_id, edit_url, edit_expires_at }`.

EditSession

For the link a respondent gets after submitting, so they can come back and change their answer.

const session = await EditSession.access(tokenFromUrl);

const current = await session.fetch();

await session.patch({ ...current.data, email: "new@email.com" });

Method	Does
`EditSession.access(token)`	Static. Exchanges an edit token for a session.
`.fetch()`	Returns the submission's current `{ id, formId, formVersion, data, status, revision }`.
`.patch(data, { draft? })`	Updates the submission. Returns `{ id, data, status, revision }`.

Errors

Every method throws a FormEngineError on failure, mirroring the API's error shape:

class FormEngineError extends Error { code: string; status: number }

Allowed image types

ALLOWED_UPLOAD_TYPES = ["image/jpeg", "image/png", "image/webp"], also exported from the package if you want to validate client-side before calling uploadFile.