Developers

Lev-Al Prose API for developers

A paid-plan API built on the same editing, MeaningLock verification and Passport signing that Workspace uses. Submitted and edited text are not stored in the application database or application-authored logs. Gateway and provider non-retention has not been independently verified; see our Privacy and Data Handling policy.

Download OpenAPI 3.1 (openapi.json)

Authentication

With an active paid plan, create an integration key in your account. It is shown once; we store only a hash.
Give the key only the scopes it needs. Revoked keys stop working immediately.
Send it as Authorization: Bearer lvp_…. Never put a key in a URL — such requests are refused.

Scopes: contract:createedit:runverify:rundocument:runpassport:createpassport:verify

Base URL: https://levalprose.com/api/v1. All endpoints accept POST with a JSON body. Rate limit: 30 requests per minute per key.

Endpoints

Endpoint	Scope	What it does
POST /contracts	contract:create	Build a MeaningLock contract. No words deducted.
POST /edits	edit:run	Edit one passage (1–500 words) into three revisions, each verified.
POST /verifications	verify:run	Verify a revision against its source. No words deducted.
POST /documents	document:run	Edit pasted text up to 5,000 words in 500-word sections. Pasted text only — no .docx.
POST /passports	passport:create	Sign a Fidelity Passport from a server receipt for a fully verified revision. No words deducted.
POST /passports/verify	passport:verify	Check a Passport's Ed25519 signature. No words deducted.

Modes

faithful (default) — natural length; no padding toward the source count.
exact_length — exact target_words (defaults to the input count), or Review required.
tighten — shorter (max_words or reduction_percent) without removing locked meaning, or Review required.

Accounting

Only /edits and /documents use words. Both need an Idempotency-Key header.
The original input word count is deducted once, only after success. Failed runs are refunded in full.
Reusing an Idempotency-Key never deducts twice; results are not stored in the application database, so use a new key to run again.
Monthly words are used before Extra Words. The free passage cannot be used through the API.

Verification and Passports

/verifications uses the same independent meaning review as Workspace. If that review is unavailable, the verdict is Review required, never Preserved.
Every /edits, /verifications and /documents revision carries a server receipt. To sign, send the source, the revision and that receipt to /passports; the server re-checks everything and never signs self-declared statuses. An edited revision needs a fresh /verifications call first.
Only revisions where every check is verified can be signed. Failed or Review required revisions are never signed.
A valid signature confirms the Passport is authentic and unaltered. It does not prove the source facts are true or prove authorship.
A Passport holds counts, statuses and salted digests — no passage text. Public key: /.well-known/lev-al-passport-key.json.

Integrations: what is available

REST API — available now on paid plans, as documented on this page.
MCP server — available now at https://levalprose.com/mcp (JSON-RPC over HTTP). Send your integration key as Authorization: Bearer lvp_…; it uses the same scopes, limits and accounting as the REST API.
Microsoft Word, Google Docs and Overleaf — development builds only. They are not listed in Microsoft AppSource, Google Workspace Marketplace or the Chrome Web Store, and are not publicly installable yet. Until they are, use the REST API or MCP, or paste text into the Workspace.

Errors

Errors return { "error": { "code": "…", "message": "…" } } with no prompts, stack traces or secrets.

401	unauthenticated	Missing, malformed, invalid or revoked key.
400	key_in_url	A key was sent in the URL. Revoke it and create a new one.
403	insufficient_scope	The key lacks this endpoint's scope.
402	plan_inactive	No active paid plan. The free passage cannot use the API.
402	insufficient_allowance	Not enough words left. Nothing was deducted.
429	rate_limited	More than 30 requests per minute for this key.
400	invalid_input / invalid_json / idempotency_key_required	The request is malformed.
422	too_long / invalid_document / not_verified	Input over the limit, or a revision that cannot be signed.
415	pasted_text_only	The documents endpoint needs a JSON "text" field.
409	idempotency_replayed / request_in_progress	Same Idempotency-Key reused. Nothing was deducted again.

Examples (synthetic text)

Requests only. Responses follow the schemas in openapi.json.

Edit a passage

curl -X POST https://levalprose.com/api/v1/edits \
  -H "Authorization: Bearer $LEVAL_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: edit-2026-10-22-0001" \
  -d '{
    "mode": "faithful",
    "text": "The pilot program may reduce wait times by 12% (Rivera, 2024), but the sample was small."
  }'

Verify a revision

curl -X POST https://levalprose.com/api/v1/verifications \
  -H "Authorization: Bearer $LEVAL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "mode": "exact_length",
    "source": "The results do not support a causal link.",
    "revision": "The findings do not establish a causal link."
  }'

Edit pasted document text

curl -X POST https://levalprose.com/api/v1/documents \
  -H "Authorization: Bearer $LEVAL_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: doc-2026-10-22-0001" \
  -d '{ "mode": "tighten", "reduction_percent": 15, "text": "First paragraph...\n\nSecond paragraph..." }'

Verify a Passport

curl -X POST https://levalprose.com/api/v1/passports/verify \
  -H "Authorization: Bearer $LEVAL_API_KEY" \
  -H "Content-Type: application/json" \
  -d @passport.json