If you are a business that is generating a large number of documents that you want to sign then then this page contains the information you need to know.
The API allows you to send us the "hash" of the doucment you want to sign and your digital signature.
When we receive this information we store it for a period of time (default is 100 days). And whilst it is stored any user that come to this website and drag/drops the document will see that it is authentic and can download a certificate or proof of its authenticity.
Documentation is all on our GitHub repository
https://github.com/umpint/rest-api
We have sample code for a number of languages this is also available on our GitHub repositories
https://github.com/umpint/bash-api
https://github.com/umpint/nodejs-api
https://github.com/umpint/java-api
https://github.com/umpint/python-api
If you do not have access to you TLS private key then this application will resolve your issues. You can run standalone, as a docker image or we can host for you on a subdomain. You then can request the web application to sign documents for you avoiding any issues with keys or signing.