Side by side
Blueink eSignature API vs OpenSign
Both stand on e-signature apis software. Which one you can start free with, which one lets you read the code, and what each costs once you pay.
Free plan APIWeb
Visit Blueink eSignature API 
Free plan Open source APILinuxMac+3
Choose OpenSign if you need a free PDF signing plan, reusable templates, or self-hosting options. Look elsewhere if your free workflow depends on bulk sending, public links, or live API tokens, since those require paid plans.
Visit OpenSignThe facts
| Blueink eSignature API | OpenSign | |
|---|---|---|
| Free plan | Yes | Yes |
| Open source | Not published | Yes |
| Runs on | API, Web | API, Linux, Mac, Self-hosted, Web, Windows |
| Lowest paid plan | Bronze (annual): $90 a month | Professional: $9.99 a month |
| Plans published | 7 | 4 |
| Maker | Not published | Not published |
| Website | developer.blueink.com | opensignlabs.com |
| On e-signature apis software | #4 of 26 | #1 of 26 |
Blueink eSignature API: what it does well
OpenSign: what it does well
- Free plan includes unlimited digital signatures and templates.
- Templates support pre-placed widgets and reusable documents.
- Supports two-factor authentication and passkey sign-in.
- Offers Docker self-hosting instructions for Linux, macOS, and Windows.
- Sandbox API tokens are available on every plan.
What to know first
- Free users can send up to 15 invitation emails per month.
- Bulk sending and public links require a paid plan.
- Live API tokens require Professional or Teams.
- Some SMTP features are limited to paid plans.
Alternatives to Blueink eSignature API Alternatives to OpenSign The whole list