
DocRaptor
Doczilla
wkhtmltopdf
PDF Generator API
DocuSign
MailMergic
HTML PDF API
PDF filling API that makes it easy to fill out PDF forms and convert HTML to PDFs

Decode and verify SSL/TLS certificates online. Extract X.509 details including issuer, validity, SAN, and fingerprint. Fast, secure, and browser-based.

Which is more popular?
Based on our record, DocSpring should be more popular than Cert Decoder. It has been mentioned 5 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | docspring.com | certdecoder.com |
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| Platforms | — | |
| Company | Startup from the United States · 1 - 9 employees · 2017 | — |
| Listed in |
In their own words, as submitted to SaaSHub.


We provide a PDF filling and generation API: Upload your PDF to our visual template editor to set up form fields and data types Post JSON to fill out existing PDF forms with data Generate editable PDF forms, or overlay static data on top of fields Create HTML/CSS templates with Liquid fields,...
Cert Decoder is a free online tool that helps you decode X.509 SSL/TLS certificates in PEM format. It instantly shows important information like the issuer, expiry date, SAN entries, and fingerprint. All data is processed locally in your browser, so nothing is ever sent or stored elsewhere.
What each product offers, as listed by its team.


Possible disadvantages
An editorial look at what each product does well and who it suits.


No analysis of DocSpring yet.
Overall verdict
Why this product is good
Recommended for
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing DocSpring and Cert Decoder.
DocSpring's answer
Ruby on Rails, React, AWS
Cert Decoder's answer:
certdecoder.com was built using just JavaScript and HTML—simple, fast, and with all processing happening locally in your browser, so no certificate data is sent to any server
DocSpring's answer
DocSpring is built specifically for developers who need reliable, secure PDF generation in production. We combine PDF form filling and HTML-to-PDF in a single API, with a visual template editor, typed fields, and validation to catch issues early. Our product has a lot of power features and is built to handle very advanced forms. Our infrastructure is SOC 2 Type II compliant, battle-tested, privacy focused, and optimized for high-volume workloads, so you can ship PDF features quickly and then stop thinking about them.
DocSpring's answer
DocSpring is designed for teams who need a powerful tool with all the features you need for complex forms and business logic. DocSpring supports structured JSON, typed fields, and array iterations, and many other advanced features, so your templates stay aligned with your real data model. You get powerful validation, a visual editor, strong observability, and an API that fits into modern engineering workflows, so you spend less time fighting PDFs and more time shipping product.
Cert Decoder's answer:
Simple, fast, and reliable. Some similar tools can’t even decode basic certificates. I rigorously tested my tool with many real-world certificates and covered several edge cases where competitors fall short.
DocSpring's answer
DocSpring is built for engineering and product teams who manage complex documents in production: things like financial applications, insurance forms, healthcare and legal documents, HR and payroll workflows, and government-style forms.
Cert Decoder's answer:
certdecoder.com is primarily built for developers, sysadmins, cybersecurity enthusiasts, and DevOps engineers.
DocSpring's answer
I used to work at a payroll company (Gusto). We had built a similar in-house tool for filling out tax forms. I then built the first version of DocSpring (formerly named FormAPI) while I was living in Thailand. I built it to automate the filling out of visa application and visa extension forms, but realized that it could also be used for tax forms, real estate contracts, and any other kind of fillable PDF form.
Cert Decoder's answer:
I built certdecoder.com over the weekend for my own needs. Sometimes in my work, I need to verify and check certificate details.
DocSpring's answer
Cert Decoder's answer:
certdecoder.com is primarily built for developers, sysadmins, cybersecurity enthusiasts, and DevOps engineers.
Share your experience with using DocSpring and Cert Decoder. For example, how are they different and which one is better?
Recommendations tracked on public social media and blogs since March 2021.


I'm still working on DocSpring [1], originally launched on Hacker News in October 2017 under the name "FormAPI." It's a PDF generation API with a template editor UI for setting up fields on PDF forms. It makes it easy to turn complex tax... - Source: Hacker News / over 1 year ago
For programmatic filling of PDFs, have a look at DocSpring: https://docspring.com. - Source: Hacker News / over 2 years ago
Great post. I've spend a lot of time reading through the PDF specification over the last ~5 years while building DocSpring [1], and I still feel like I've barely scratched the surface. Qpdf is a great tool. One of my other favorites is... - Source: Hacker News / about 3 years ago
Why? Because I built certdecoder.com and couldn’t find a decent place to submit it. So I said screw it — I’ll build my own. With blackjack and hookers. - Source: dev.to / over 1 year ago
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