BoldSign vs SignatureAPI (2026): which should you pick?
As of Nov 13, 2026, we pick BoldSign: it is first in our ranking of e-signature and proposal tools, and it grades higher too, 3.0 against 2.0.
Checked Nov 9, 2026 and Nov 13, 2026 · graded Oct 17, 2026 and Nov 13, 2026 by ToolGPA
BoldSign grades higher on value for money, the free plan, features and ease of use. They get the same grade on platforms.
Price, platforms and features side by side. The table says where each price was read and when.
BoldSign
Low-cost e-signature app and API from Syncfusion
SignatureAPI
E-signature API for developers, with a no-code connector
Which one is for you
Pick BoldSign if
- Fits if you send up to 25 documents a month and don't want to pay anything
- Works for small teams at $5 a head billed yearly, or nonprofits, who get Growth free
Look elsewhere if
- Tight if you each send more than 50 documents a month on Growth, as unlimited needs Business at $15 a head
- Pricey if you bulk send often, as bulk send, SMS, WhatsApp and ID checks are charged on use
- Not for you if you need the API, which is a separate plan from $30 a month, then $0.75 an envelope
- Watch out: Premium shares 250 envelopes a month across all users and bills pay-as-you-go past that
- Watch out: trial accounts on public email domains get lower limits, and the free plan holds 2 templates
Pick SignatureAPI if
- Fits if you are building signing into your own product
- Works for developers who want to pay per completed envelope
Look elsewhere if
- Not for you if you have no developer, since it is an API with only connectors for no-code
- Watch out: the signatures are eIDAS simple only, not advanced or qualified
- Tight if your envelopes are large, as the limit is 10 documents and 10 signers
- Watch out: annual billing and prepaid credits are not self-serve
How we grade them
| 3.0GPABoldSignVery good | 2.0GPASignatureAPIFair | |
|---|---|---|
| Value for money | A$15 a month for three on Growth, billed yearly ($5 a head, $15 a head monthly), with 50 envelopes each a month and 10 templates. That's under 60% of this category's cheapest quarter. Unlimited envelopes on Business is $15 a head. | CStandard is $25 a month with 100 envelopes included, then $0.25 each, just above the category's $20 middle. Extra dashboard users are $20 each. |
| Free plan and trial | BThe free Essential plan gives one user 25 envelopes a month, 2 templates, signer authentication, reminders, branding and the apps. One person could really live on that. Paid plans have a 30-day trial too. | CA free test account with no time limit and no card, but it is for testing, and sending for real needs Standard. |
| Features | BSigner authentication on every plan, templates, in-person signing and team sharing on Growth, then SSO, AI field detection and HubSpot on Business. Bulk send, SMS, WhatsApp and ID checks cost extra on use, but they're there. It covers the whole job. | CEnvelope API, templates, signing with no account, sealed documents, audit log, branding and webhooks. An envelope holds at most 10 documents and 10 signers, and signatures are simple only. |
| Ease of use | CThere's an iPhone app but no store rating on record yet. It's a web app where you upload a contract, place fields and send, with templates to set up first. | DNo store rating on record, and it needs developers to write code against an API before anyone signs anything. |
| Platforms and integrations | BWeb, iPhone and Android, with Salesforce, HubSpot, Zapier, Xero and Power Automate, plus an API on its own plan from $30 a month. No desktop app, so it's a B. | BWeb and API, with Power Automate and Zapier connectors. |
| Best for | e-signatures from $5 a user, with a free plan for one | adding e-signatures to your own app |
The GPA is the average of the five grades: an A is 4 points, an F is none. The full reasons are on each tool's page: BoldSign and SignatureAPI. How we grade
Price against what you get
BoldSign starts at $5 a month for each person and scores 2.7 out of 4 on features, ease of use and platforms. SignatureAPI starts at $25 a month and scores 2.0.
BoldSign scores higher and starts $20 a month lower. Of the other e-signature and proposal tools on the chart, none scores higher than BoldSign for less, and 29 score higher than SignatureAPI for less.
Features, ease of use and platforms, averaged
What paid plans start at, a month (each step along is roughly double) →
- The best score at each price
- Has a free plan
- No free plan
Where they differ
- BoldSign also covers documents.
- SignatureAPI also covers workflow automation and AI agents.
At a glance
| BoldSign | SignatureAPI | |
|---|---|---|
| Pricing | Free plan | Free trial |
| Starts at | $5 per user / month, billed yearly ($15 billed monthly) | $25 per month, includes 100 completed envelopes |
| Free plan | Essential plan: one user, 25 envelopes a month and 2 templates, with an audit trail, signer authentication, reminders, branding and the mobile apps. | None |
| Free trial | 30-day free trial; accounts on public email domains get lower trial limits | Free test account with no time limit, no card required |
| Web | ||
| iOS | ||
| Android | ||
| Made by | Syncfusion | Signature API, Inc. |
| Price read from | boldsign.com | signatureapi.com |
| Checked | Nov 9, 2026 | Nov 13, 2026 |
Worth knowing
BoldSign
- Growth caps each user at 50 envelopes a month and 10 templates; unlimited envelopes need Business.
- Bulk send, bulk links, SMS and WhatsApp delivery, ID verification and the Salesforce integration are add-ons charged on use.
- The API is a separate plan: from $30 a month with 40 envelopes, then $0.75 per envelope.
- Premium shares 250 envelopes a month across all users; each envelope past that costs $0.50.
SignatureAPI
- Only completed envelopes, signed by every recipient, are billed; the $0.25 rate applies after the first 100 each month.
- An envelope holds at most 10 documents and 10 signers.
- The vendor classifies its signatures as eIDAS simple electronic signatures (SES), not advanced or qualified ones.
- Annual billing and prepaid credits are not self-serve; the vendor says to contact it.
Key features
BoldSign
- Email, SMS or WhatsApp delivery
- Send signing requests by email on every plan; SMS and WhatsApp delivery are paid add-ons from the Business plan.
- Templates and bulk sending
- Save contracts as templates and share them with a team; bulk send from a CSV file and bulk signing links are add-ons.
- Signer verification
- Signer authentication is on every plan; ID with selfie checks, knowledge-based questions and SMS codes can be added on Business.
- AI field detection and search
- Business adds AI that places signature fields on a document and an AI search across signed documents.
- Audit trail
- Each document keeps a downloadable audit trail of its signing history, and the final file is digitally signed to show tampering.
- API and embedded signing
- A free sandbox for testing, then an API plan with embedded sending and signing, webhooks, Zapier, Power Automate and an MCP server.
SignatureAPI
- Envelope API
- One call creates an envelope with up to 10 documents and up to 10 signers, routed in parallel or in sequence.
- Document templates
- Start from a .docx file with placeholders and fill it with data from your own system before the document goes out for signature.
- Accountless signing
- Signers open a link and sign from a desktop or phone browser without creating an account.
- Sealed documents and audit log
- The finished file holds the signed documents and a log of who opened it and what they did, cryptographically sealed against changes.
- Branding and languages
- Logo and brand colors can be applied to the signing page and recipient emails, and the interface language, date format and time zone can be set.
- Webhooks and no-code connectors
- Webhooks and emails report signing activity in real time. Power Automate and Zapier connectors and an AI toolkit are offered for non-developers and agents.
Plans
BoldSign
Essential$0
One user, 25 envelopes a month and 2 templates, with an audit trail, signer authentication and reminders.
Growth$5
per user / month, billed yearly ($15 billed monthly)
50 envelopes per user a month and 10 templates, with template sharing, in-person signing and team management.
Business$15
per user / month, billed yearly ($25 billed monthly)
Unlimited envelopes and templates, SSO, custom roles, AI field detection and search, HIPAA and the HubSpot integration.
Premium$99
per month for up to 250 envelopes, billed yearly ($138 monthly)
Everything in Business for unlimited users, sharing 250 envelopes a month.
SignatureAPI
Standard$25
per month, includes 100 envelopes
First 100 envelopes included, then $0.25 each. One dashboard user included, extra users $20 each.
EnterpriseCustom
Annual contracts, prepaid credits, SLAs and dedicated Slack support, sold through sales.
Ways to pay less
BoldSign
- Annual discount
Save 40% with yearly billing
BoldSign's pricing page marks yearly billing as 40% off: Business is $15 per user a month billed yearly against $25 monthly.
- Nonprofit
Free Growth plan and 50% off for nonprofits
Nonprofit organizations get the Growth plan free and 50% off the Business and Premium plans.
SignatureAPI
No public discounts listed.
Common questions
Which is cheaper, BoldSign or SignatureAPI?
As of Nov 13, 2026, BoldSign starts at $5 per user / month, billed yearly ($15 billed monthly), and SignatureAPI starts at $25 per month, includes 100 completed envelopes. One is priced for each person and the other is not, so which costs less depends on how many of you use it.
Which has a free plan, BoldSign or SignatureAPI?
As of Nov 13, 2026, only BoldSign has a free plan. SignatureAPI does not, though it has a free trial.
Which platforms do BoldSign and SignatureAPI run on?
As of Nov 13, 2026, only BoldSign lists iOS and Android apps. Both list a web app. A platform missing from a listing is one its maker's pages did not mention.
More comparisons
How this page was made
- The verdict at the top follows a fixed rule. When both tools are in the same category and either is in our top three for it, the verdict follows that ranking: the higher-placed tool is our pick. The top three weigh who each tool suits as well as its grades, so a pick can go against the GPA. Otherwise the page does not pick one and says which grades higher: the higher GPA first; on a tie, the one with a free plan, then the one that starts cheaper in dollars a month, counted the same way for both; if they are still level, what the choice depends on.
- The grades are our own, from each tool’s review or report card. The GPA is their average.
- Prices, plans and platforms come from each tool’s listing. The table above says where each price was read and when.
- The differences and the answers to the questions are worked out from those listings.