Most e-signature vendors bill the API separately from the web app, so the seat price you were quoted buys the browser UI and nothing else. Signvoy puts the REST API, signed webhooks, and the MCP server on every plan — including the free one — with keys you issue yourself.
The part nobody puts on the pricing page
The API is almost never in the price you were quoted
Read an e-signature pricing page and you will find a row of per-seat numbers that look comparable to each other. They are not comparable to anything you are about to build, because for most vendors in this market the REST API lives on a different plan — sometimes a different product line — from the seats.
DocuSign is the clearest case. Its Personal and Standard plans carry no developer account and no API at all; the first tier that includes them is Business Pro, and the envelope allowance is metered per user per YEAR rather than per month. Dropbox Sign separates the two outright: its API Essentials plan is its own product at $75 a month for 50 signature requests, and embedded signing is not in that tier — the next one up is $250 a month. BoldSign is the most transparent of the three and still gates the API behind a $30-a-month Enterprise API plan that none of its four web-app tiers include.
PandaDoc is worth a separate note because it changed recently. The API is no longer Enterprise-only and now appears on the $19 Starter plan — but it runs on prepaid Usage Credits, and PandaDoc states plainly that API usage is credit-pack only with no pay-as-you-go. When the credits reach zero the calls are rejected. That is a different shape of cost from a monthly fee, and it is easy to miss when comparing seat prices.
None of this is hidden exactly. It is simply never on the page you are comparing. The table below puts the API plan next to the API plan.
| Product | First plan with API access | Price | Included volume |
|---|---|---|---|
| Signvoy | Free | Free | 10 documents per month, then $10/mo for unlimited |
| BoldSign | Enterprise API | $30/mo | 40 envelopes per monththen $0.75 per envelope |
| DocuSign | Business Pro | $45/user/mo | 100 envelopes per user per YEARthen Pay-as-you-go per envelope, rate not published |
| Dropbox Sign | API Essentials | $75/mo | 50 signature requests per month |
| PandaDoc | Starter | $19/user/mo | No included API volume |
| DocuSeal | Pro | $20/user/mo | Usage-based at $0.20/document |
| Documenso | Individual | $25/mo | Unlimited documents |
API pricing checked against each vendor's own public page on 14 October 2026. These are the plans that first include REST API access, which for most vendors is not the plan the advertised seat price buys. Vendors who publish no public API price are marked as such rather than estimated.
To be accurate about our own position: Signvoy is not the cheapest e-signature product outright. BoldSign's web-app plans start at $5 a month and undercut our Pro tier. The narrower claim this table supports is about API access specifically — it is the one dimension where our entry price is zero, and where the gap to the next cheapest option is the whole of its monthly fee.
The second thing to check
Find out what the volume unit is, and over what period
Price is the obvious comparison. The unit that price buys is the one that actually decides your bill, and it is where this market is least readable. Three of the largest vendors meter sends per user per YEAR rather than per month, which is a difference of roughly twelve times and is almost never stated in the number a buyer remembers.
DocuSign Standard and Business Pro both include 100 envelopes per user per year on annual billing — about eight a month. Choose monthly billing instead and the allowance is restated as 10 per user per month. SignNow's Business Premium is 100 invites per user per year. Adobe Acrobat Pro for Teams is 150 transactions per user per year, and enforces a two-seat minimum on top, so its advertised per-user price understates the real entry cost by double.
None of these are hidden in the sense of being undisclosed; they are all written down somewhere. They are simply not next to the price. A developer sizing an integration against "$30 a user" and planning for a few hundred signatures a month is, on at least three major platforms, planning against an allowance that runs out in the first fortnight.
Signvoy meters documents per month and nothing else. Free is 10 a month. Pro is unlimited at $10 a month. There is no per-seat envelope allowance, no annual pool to budget against, and no separate meter for documents that happen to arrive over the API rather than the dashboard — an API document and a dashboard document are the same document.
Evaluating any e-signature API
Six things worth checking before you integrate
These are the questions that are expensive to answer late. They apply to any vendor in this category, including us — a few of them are places where we would rather you find the limit here than three weeks into a build.
Which plan actually includes the API
Start here, because it reorders every other comparison. The seat price on the pricing page frequently buys the web app alone, and the API sits on a separate plan or a separate product line. Check the plan name, not the marketing page.
Whether test keys and live keys are the same system
Some vendors give you a free sandbox whose documents are watermarked and deleted after a fortnight, then require a different plan and a different credential to send anything real. That is two integrations, and the second one is the one you cannot test. Ask whether going live is a key change or a migration, and whether a human has to approve it.
What happens when a webhook fails
Your endpoint will be down at some point; the question is what the vendor does about it. Look for signed payloads so you can verify origin, a retry schedule with real backoff rather than a single attempt, a delivery log you can inspect after the fact, and the ability to replay a delivery by hand. Without the log, a missed completion event is unrecoverable and you will be reconciling by polling.
Whether the smart-field layer is reachable in code
Conditional visibility, validation rules, and computed fields are the difference between a signing API and a forms API. Most vendors gate this behind a higher tier or a sales conversation, and some do not expose it over the API at all even where the dashboard supports it. If your documents branch on what the signer entered, confirm the rules survive the API round trip before committing.
What you can prove afterwards
An electronic signature is only as useful as the evidence behind it. The practical test is whether you can retrieve, programmatically, a record of who signed, when, from what address, and what they saw and consented to — and whether the completed file carries something tamper-evident. If a dispute means emailing support for a PDF, that is a gap in your product, not theirs.
Where the rate limits are, and what happens at them
Normal traffic rarely hits a ceiling. Migrations and backfills do, and they tend to be the first large thing you run. Find out the limit, whether it is per key or per account, and whether exceeding it throttles you or rejects outright. A vendor that will raise it on request before your migration is worth more than one with a higher published number.
Getting started
From signup to first signature request
No sandbox-to-production migration and no approval queue. A key you generate in workspace settings is a live key, and the document it sends is a real document with a real audit trail.
Create a key
Workspace settings issues an `sk_live_` key. It is shown once, stored as a SHA-256 hash, and scoped to the workspace that created it.
Send a document
Create a document from a published template, fill known values server-side, and send it to one or more recipients in whatever signing order you need.
Listen for the result
Register a webhook endpoint and handle `document.completed`. Deliveries are signed with HMAC-SHA256 and retried with exponential backoff.
Send a document for signature
curl https://api.signvoy.com/v1/documents \
-H "Authorization: Bearer sk_live_..." \
-H "Content-Type: application/json" \
-d '{
"templateId": "tpl_01h8x...",
"recipients": [
{ "name": "Priya Raman", "email": "priya@example.com", "role": "signer" }
]
}'That is the whole integration for the common case. The full surface — templates, recipients, fields, reminders, voiding, and the signed PDF — is in the API reference. API reference.
What is on the free plan
The list below is not an enterprise tier. These are the capabilities a free API key can reach on the day it is issued, which is deliberate: for a product without a brand, the API is an acquisition channel rather than a monetisation one.
REST API
Documents, templates, recipients, fields, and reminders over plain JSON. The OpenAPI specification is published, so clients generate cleanly.
Signed webhooks
Seven lifecycle events, each delivery signed with HMAC-SHA256, retried with exponential backoff, and recorded in a delivery log you can replay from.
MCP server
A Model Context Protocol server so an AI assistant can list templates, create documents, send them, and chase signatures — with the destructive operations held behind confirmation.
Conditional logic
A typed expression language for validation, visibility, and computed fields, with cycle detection at save time. Most vendors in this market gate this behind a sales conversation; it is on our free plan.
Audit trail and certificate
Every lifecycle event carries a timestamp, IP address, user agent, and actor identity. Completed documents get a tamper-evident certificate with a SHA-256 fingerprint of the signed file.
Keys you issue yourself
No application form, no go-live review, and no separate sandbox credential to migrate off. Rotate or revoke from the same screen that issued the key.
What this API does not do yet
Two things worth knowing before you build, because finding them out later is worse. There is no bulk send endpoint, so high-volume CSV-driven sends have to be loops for now. And while an embedded signing session endpoint exists and a React package is published, the signer surface cannot currently be framed by a third-party origin — treat embedded signing as not yet available rather than as something to design around. Redlining and clause negotiation are deliberately out of scope; that is contract lifecycle management and we are not pretending to compete there.
Yes, and it is the same API the paid plans use — not a reduced or sandboxed version. The free plan's limit is 10 documents a month; the API itself is not restricted. Pro removes the document cap at $10 a month.
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