Java4s VS MailMergic

MailMergic's answer:

MailMergic makes a separate, finished document for every row of a spreadsheet, and it works with the files people already have:

• Fills fillable PDF forms and writes onto flat PDFs that have no form fields
• Uses Word and Excel templates too
• Downloads each document, or emails it to its recipient as a personal attachment in the same run

Most mail merge tools do only one half of that: they either send emails or create documents.

MailMergic's answer:

Proven since 2019. MailMergic has run for over six years and generated more than 25 million documents in the past 12 months, for people in over 100 countries. Runs of 128,000+ documents complete in one go, and customers rate it 4.6 out of 5.

It is also simple. No macros, no scripts, no Word, Excel and Outlook setup that only one colleague understands.

• Upload a template and a list, drag the columns into place, check a preview with real data, and generate
• A data check catches typos before they end up in hundreds of documents
• German company, GDPR compliant and hosted in the EU
• You decide how long files are kept, from 5 minutes to 180 days
• A desktop app runs everything offline for data that must not leave the building

MailMergic's answer:

People who need the same document for many people and are not developers:

• Course and training providers issuing certificates
• Schools and universities
• Nonprofits sending donation receipts
• Accountants and HR teams filling tax and employee forms
• Event organizers printing name badges and labels
• Small businesses sending invoices and letters

They usually have an Excel or Google Sheets list and a PDF or Word template, and they don't want to fill in each copy by hand.

MailMergic's answer:

Lennart Guth founded MailMergic in 2019, after working in technology consulting at Accenture and a German bank and then building his own software startups. One of them, Pacemo, put him in front of people who spent their days on government forms, and the gap was obvious: you could mail merge a Word document, but not a PDF.

He built the first version himself and launched it as PDF Mail Merger in August 2019. It was later renamed MailMergic and added Word and Excel templates, email sending and a Google Sheets add-on.

The company is based in Eschborn near Frankfurt, has no outside investment and is funded by its customers. It has generated more than 25 million documents in the past 12 months, for people in over 100 countries.

MailMergic's answer:

• Front end: TypeScript, React, Material UI
• Back end: Node.js on Google Cloud (Firebase, Cloud Run)
• Documents: pdf-lib, pdf.js and Ghostscript for PDFs; a .NET service for Word and Excel
• Desktop app: Electron
• AI: Claude (Anthropic) and Gemini (Google Vertex AI) for the data check and form-field matching, both on enterprise terms that rule out training on customer data

MailMergic's answer:

• Largest single run: 128,195 documents
• Customer rating: 4.6 out of 5 (134 post-purchase surveys in 2025)