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Case Study

Less Admin.
More Engineering.

How Ingenieurbüro Hölzl GmbH digitised its entire project lifecycle for managing government energy subsidies. 55,000+ lines of custom code. 90 live automations. One unified system.

Ingenieurbüro Hölzl GmbH
01

The Project Pipeline Engine.

Every project follows a structured lifecycle from initial meeting through to government subsidy completion. We built the automation layer that moves projects through 21 stages, sending the right emails, generating the right documents, and notifying the right people at every step.

Project Lifecycle

21 stages, fully automated
00Meeting
5
10Proposal
9
20Data Collection
14
40Subsidy
17
50Execution
9
70Invoice
7
80Declaration
3
99Complete
156
Active pipeline 64 active / 156 completed

Automated client emails

Proposal, order confirmation, subsidy approval, invoice, and end-of-project emails sent automatically with the right attachments and templates.

Automated PDF signing

Power of attorney and declaration documents are pre-filled from project data and digitally signed without manual intervention.

Expiry + follow-up tracking

Proposals that expire are automatically flagged and archived. Completed projects can spawn follow-up projects with inherited data.

02

Every Document, In Its Place.

Over 20 dedicated Make scenarios manage the full document lifecycle on NextCloud. Folders are created, moved, and archived automatically as projects progress. Every file lands in the right subfolder with the right name.

Auto-Created Folders

Per-type folder structures generated on project creation.

Auto-Moving by Stage

Folders relocate between directories as projects progress.

Client Uploads

External submissions auto-sorted into the right subfolder.

Follow-Up Copying

Spawned projects inherit all files from the original.

cloud.example.com/Projekte
/ Projekte
01 - Acquisition 8 projects
02 - Active Projects 42
PRJ-2843 - Braun
PRJ-2847 - Mueller 5 folders
Angebot 2 files
Vollmacht 1 file
Rechnungen 3 files
Technische_Unterlagen 4 files
Kundendaten 2 files
PRJ-2851 - Weber
03 - Archive 156
03

Custom-Built Interfaces.

React/TypeScript extensions built directly into Airtable, giving the team tailored views and editing tools that go far beyond what default interfaces offer. 11,000+ lines of frontend code.

Projects Summary

Real-time pipeline view of all 64 active projects across three government subsidy programs. Kanban columns match each project's approval stage, with drag-and-drop to advance status.

All Projects
Kanban List Pipeline
EBW
28
BEG EM BAFA
22
EB
14
10 - Proposal Sent 9

PRJ-2891

EBW

Musterstr. 12, Berlin

K. Richter

PRJ-2894

BEG

Hauptweg 5, Munich

M. Braun
20 - Add. Documentation 14

PRJ-2847

EB

Gartenstr. 8, Stuttgart

S. Weber

PRJ-2853

EBW

Ringweg 22, Hamburg

L. Fischer
40 - Awaiting Approval 17

PRJ-2812

EBW

Birkenstr. 3, Cologne

H. Braun
70 - Invoicing 7

PRJ-2798

BEG

Waldstr. 14, Frankfurt

A. Koch
9
3

Email Template Configuration

Each project status has a matching email template with dynamic placeholders that auto-fill from project data. Staff select a status, and the email writes itself.

10 - Proposal Email (EBW) Status 10
Revert Save
Content Preview Advanced

Subject

Angebot: {{project_name}}

Body

Sehr geehrte/r {{client_salutation}},

anbei erhalten Sie unser Angebot fur {{project_type}} Massnahmen...

Forderfahig bis: {{subsidy_amount}}

Attachments

Angebot_{{prj_id}}.pdf
Vollmacht_{{prj_id}}.pdf

Auto-Tasks Manager

Configurable task templates that auto-generate when a project changes status. Defines who does what, when it's due, and who gets notified.

Send Proposal Status 10 EBW
Content Automation Preview Notifications

Title (DE)

Angebot erstellen und versenden

Title (EN)

Create and send proposal

Description

Generate proposal document using project data, attach signed Vollmacht, and send to client via email template.

Trigger

On Status Change

Assignee

AT
A. Teufel

Due Offset

+3 days
Teams notification on creation + email to client on completion
04

Accounting, Fully Synced.

A custom sync service connects Lexware (the German accounting standard) with Airtable in real time. Customers, quotations, invoices, suppliers, and payroll all flow into a single financial dashboard built as an Airtable extension.

Lexware Two-Way Sync

Customers, invoices, quotations, order confirmations, suppliers, and payroll sync continuously between Lexware and Airtable.

Invoice PDF Vouchers

PDFs are uploaded via Cloudinary and attached to Airtable records. Revenue reporting stays accurate without manual entry.

Job Queue with Dependencies

Sync jobs run in dependency order with reconciliation, conflict handling, and a full audit trail.

Revenue by Project Type

Automatic breakdown by subsidy program. Year-over-year comparisons, profit margins, and pipeline forecasts update in real time.

Financial Overview
Sync Lexware Sync Payroll

Active Quotes

€84,200

3 expiring

Pipeline

€127,500

14 projects

Receivables

€31,840

2 overdue

Payables

€12,680

6 invoices

Revenue & Expenses

2024 2025
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Revenue
Expenses
Revenue €482,300
Expenses €218,600
Margin 54.7%

By Project Type

EBW
€248k
BEG EM BAFA
€156k
EB
€78k

Projects Funnel

Quoted
€312k
Accepted
€224k
Invoiced
€172k
Paid
€138k
05

The Backend That Runs It All.

A custom Python/FastAPI service that ties every system together. It handles document generation, file management, email processing, automated task workflows, notifications, and data protection, all through a single, secure API.

21K+

Lines of Python

12

Modules

6

Integrations

100%

Idempotent

Utilities API v2.4.1
Uptime 99.97% Operational

Active Modules

PDF Signing

1,247

documents signed

Task Engine

3,891

tasks processed

Email Sync

2,156

emails parsed

Notifications

6,420

Teams alerts sent

NextCloud

8,340

file operations

Backups

365

daily backups run

Contact Sync

482

contacts synced

URL Shortener

934

links created

Recent Activity

PDF Signed Vollmacht PRJ-2847

Uploaded to NextCloud/Projects/2847/

2m ago

Task Created "Send BEG confirmation"

Auto-triggered by status: Bewilligt

5m ago

Email Synced from mueller@example.de

Matched to PRJ-2831, contact linked

8m ago

Teams Alert Project status: Abgeschlossen

Sent to #projekte channel

12m ago

Requests This Week

Mon Tue Wed Thu Fri Sat Sun

Top Endpoints

/api/workflows/on-status-change
342
/api/email/sync
251
/api/sign-document
152
/api/nextcloud/move
124

Document Generation + Signing

1

Project data pulled from Airtable

2

Vollmacht/POA/declaration PDF pre-filled

3

Digital signature applied

4

Uploaded to NextCloud project folder

Task Lifecycle Engine

1

Project status changes in Airtable

2

Template-driven tasks auto-created

3

Eligible tasks auto-completed on conditions

4

Teams notification sent to assigned staff

Email Sync + Project Linking

1

Inbound email received via Mailhook

2

Parsed, de-duplicated, forwarding detected

3

Auto-matched to project + contact

4

Stored in Airtable with attachments

Backup + GDPR Compliance

1

Daily automated Airtable backup to NextCloud

2

Schema auto-discovered, all tables exported

3

Old backups cleaned with retention policy

4

GDPR deletion clears sensitive data on archive

06

Connected to Everything.

The platform ties together every tool the team uses. No more switching between apps. No more manual data entry across systems.

55K

Lines of Code

Across 3 codebases

90

Make Automations

Orchestrating the full lifecycle

44

Custom Fillout Forms

Data entry + client facing

23

Airtable Tables

Interconnected data model

100+

Projects Completed

And counting

invoices files alerts forms contacts bookings
Airtable
Lexware

Lexware

Accounting

NextCloud

NextCloud

Documents

Microsoft Teams

Microsoft Teams

Notifications

Fillout

Fillout

44 Forms

Fritz!Box

Fritz!Box

Phone Sync

Zeeg

Zeeg

Scheduling

About Costanera

We Build Things
That Get Used.

Costanera is a boutique software studio that builds custom automation and software for businesses across all industries. One team, no fluff, shipped fast. This engineering consultancy has been a client since May 2025, with over 150 features delivered and counting.

Tech stack

Airtable Make.com Python / FastAPI React / TypeScript NextCloud Fillout Lexware API Cloudinary MS Teams Zeeg +more
costanera.uk

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