What Seitenbau does

SEITENBAU GmbH is an owner-managed German IT services and software company headquartered in Konstanz (with offices in Berlin and Köln), founded in 1996 and serving the German public sector as its primary client base. The company develops and operates a portfolio of digital government platforms — most notably Social OfficeNet (SON), a bundeseigene (federal-government-owned) social intranet and knowledge-management platform used by approximately 300 federal institutions and ~300,000 federal employees; the state-level service portals service-bw (Baden-Württemberg) and Amt24 (Saxony), maintained since 2015; and the OZG-Hub, an interoperability layer for the Onlinezugangsgesetz (OZG) co-developed with the Baden-Württemberg Ministry of the Interior and the Saxon State Chancellery that enables modelling of EfA-compliant digital citizen services across all 16 German states. SEITENBAU also provides register-modernization consulting and implementation work tied to NOOTS (Nationaler Online-Diensttracker und Once-Only-Tech Stack), including the first live use case for the resident-parking permit.

The underlying platform architecture is built on open-source components — Node.js/React/Express for the SPA frontend, Spring Framework with JPA/Spring Data for backend services, RabbitMQ for messaging, Keycloak/OpenID Connect (with Kerberos) for authentication, and Solr for search — deployed via container-based architecture (Docker, Podman) with horizontal scalability from hundreds to thousands of users. SEITENBAU operates its own automated operations service ('Kona') and supports both on-premise (typical for government clients) and OpenShift-compatible cloud deployment.

Commercially, SEITENBAU generates revenue through project-based professional services (software development, consulting, implementation, training, support) priced under framework agreements and time-and-materials contracts with German public administration bodies; for SON specifically, eligible government agencies pay an annual development contribution scaled to user count, with 100% of contributions flowing back into product development under the 'Alle für Alle' contribution principle. No commercial license fees are charged for SON. The go-to-market is sales-led and consultative, driven by invitations to public tenders, multi-year framework contracts, and direct relationships with federal ministries, state governments, and federal agencies. The customer roster spans federal ministries (Bundeskanzleramt, Innenministerium BW, Sächsische Staatskanzlei), federal agencies (BVA, Bafin, KBA, ITZBund, Statistisches Bundesamt, Deutsche Rentenversicherung), select private-sector clients (Deutsche Telekom), and one Swiss federal entity. SEITENBAU is privately held by its owners, has no external private equity or venture capital backers, and operates the wholly-owned subsidiary Laut.AG (digital music media).

Name

Seitenbau

Legal name

SEITENBAU GmbH

Website

https://seitenbau.com

Company type

Private

Founded year

1996

Operating status

Operating

Headcount range

1–10 employees

Short description

SEITENBAU GmbH is an owner-managed German IT firm founded in 1996 that develops and operates digital government platforms — including Social OfficeNet (SON), service-bw, Amt24, and OZG-Hub — for German federal, state, and municipal authorities, generating revenue through framework-based professional services and per-user development contributions.

Ownership category

akta.pro rank

Headquarters

HQ city

Konstanz

HQ country

Germany

HQ region

Europe

Offices3 records

Markets served

GTM type

B2B

Offering type

Services

Cost components

Personnel, Technology or R&D, Operations, Marketing or Sales, Infrastructure

Revenue model

1. Software Development & Consulting Services: SEITENBAU generates revenue through project-based professional services engagements with German public administration bodies and private sector clients. Engagements include software development, consulting, implementation, and support services, typically structured as framework agreements or time-and-materials contracts. For Social OfficeNet (SON), government clients pay annual development contributions for ongoing maintenance and feature development, channeled through support contracts. No commercial license fees are charged for SON; all contributions fund product development directly.

Pricing tiers

Go-to-market motion1 record

Distribution channels2 records

Marketing channels6 records

Core offering

SEITENBAU develops, operates, and continuously evolves proprietary e-government software platforms (Social OfficeNet, service-bw, Amt24, OZG-Hub, OZG-PLUS Postfach) for German federal, state, and municipal authorities, and delivers associated consulting, implementation, and training services. The company combines custom software development with deep domain consulting to help public sector clients comply with OZG, modernize administrative registers, and provide digital citizen services.

Product overview

Seitenbau is a German IT services and solutions company serving public administration, offering a portfolio of interconnected digital government platforms. The core product suite comprises Social OfficeNet (SON) — a social intranet and collaboration platform for federal agencies — alongside state government service portals service-bw (Baden-Württemberg) and Amt24 (Saxony). These are complemented by the OZG-Hub platform, which acts as an interoperability layer for the Online Access Act (OZG), and the OZG-PLUS Postfach digital mailbox component. Consulting services cover register modernization and OZG implementation. The overall architecture is built around enabling end-to-end digital administrative services, with platforms designed to interconnect via standardized interfaces and third-party identity and payment systems.

Differentiator

Problem solved

Functional benefit

Brands

• Social OfficeNet (SON): A federal government-owned software solution providing out-of-the-box social intranet and knowledge management functions for government agencies, developed by SEITENBAU.
• service-bw
• Amt24
• OZG-Hub
• Social Intranet des Bundes (SIB)

Products and services

• Social OfficeNet (SON) Government-owned social intranet and knowledge management platform providing activity streams, document sharing, video conferencing, and integration with enterprise communication tools for German federal, state, and municipal agencies. License-free for eligible authorities, with annual per-user development contributions funding ongoing product development.
• service-bw State-owned e-government service portal for Baden-Württemberg that enables citizens and businesses to access and complete administrative services online.
• Amt24 E-government service portal platform for Saxony providing citizens with centralized access to administrative information and online services.
• OZG-Hub Online service hub platform that acts as an interoperability layer for the Onlinezugangsgesetz (Online Access Act), connecting citizens and businesses to multiple administrative services through a single digital entry point, with an intuitive form designer, pre-built process modules, and nationwide usable interfaces.
• OZG-PLUS Postfach Digital mailbox component integrated into the OZG ecosystem that enables secure electronic communication and document exchange between citizens, businesses, and public administration bodies, including participation in electronic legal communications (Justizkommunikation).
• Registermodernisierung (Register Modernization) Consulting and Implementation Technical consulting and implementation services for the modernization of German public administration registers, supporting the federal initiative to digitize and interconnect government databases and to implement the Once-Only principle.
• Workshops and Training Specialized workshops and training programs for public administration clients, covering topics such as service-bw, Amt24 administration, FIT-Connect integration, OZG implementation, and digital transformation roadmaps, delivered online and on-site (in-house).

Quantifiable outcome

• SON is used by approximately 300 federal institutions with ~300,000 potential users across the German federal administration.
• +3 more outcomes

Named customers16 records

Segments2 records

Ideal customer profiles2 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature6 records

Partnerships

Eleven partnerships are on record, tiered minor and core.

• Laut.AGminorOthersLaut.AG is a subsidiary of SEITENBAU GmbH. It operates the music magazine lauf.de, the online radio platform laut.fm, and other offerings of the digital music media house from Lake Constance.
• GovernikuscoreTechnology or IntegrationSEITENBAU supports the IT service provider Governikus in implementing the extended business mailbox (OZG-PLUS Postfach), an additional functionality for Mein Unternehmenskonto (MUK) based on ELSTER. This enables participation in electronic legal communications (Justizkommunikation).
• ITZBund (Informationstechnikzentrum Bund)coreImplementation/ SI/ Consulting PartnerThe ITZBund is responsible for the smooth technical operation of the Social Intranet des Bundes (SIB). SEITENBAU develops the SIB Dachportal while ITZBund handles production hosting and operations. ITZBund also conducts periodic security reviews of SON with BSI.
• FITKO - Föderale IT-KooperationcoreStrategic or Co-development PartnerFITKO (Federal IT Cooperation) is a key partner in the OZG-Hub initiative and register modernization. SEITENBAU collaborates with FITKO on NOOTS Use Case implementation and federal digital administration standards.
• Innenministerium Baden-Württemberg (Ministry of the Interior of Baden-Württemberg)coreStrategic or Co-development PartnerJointly with the Saxon State Chancellery, SEITENBAU co-initiated the OZG-Hub platform with the Ministry of the Interior of Baden-Württemberg. The ministry oversees the E-Government domain as part of the joint IT strategy of the federal and state governments.
• Sächsische Staatskanzlei (Saxon State Chancellery)coreStrategic or Co-development PartnerJointly with the Baden-Württemberg Ministry of the Interior, SEITENBAU co-initiated the OZG-Hub platform with the Saxon State Chancellery. Saxon government bodies also use the Amt24 service portal developed by SEITENBAU.
• OfficeNet/SON Fachverbund (Professional Association of SON-using Authorities)coreStrategic or Co-development PartnerAll authorities using OfficeNet/SON are members of the Fachverbund. The Fachverbund collectively takes on the Product Owner role for SON, steering development, setting priorities, and participating in agile ceremonies. SEITENBAU serves as the development partner. This unique governance model ensures all general-purpose enhancements flow back to the shared code base.
• Bundeskanzleramt (Federal Chancellery)coreStrategic or Co-development PartnerThe Federal Chancellery initiated the Social Intranet des Bundes (SIB) and oversaw its launch in August 2019 under the joint IT strategy of the federal government.
• Bundesverwaltungsamt (Federal Administration Office)coreStrategic or Co-development PartnerPartner in the NOOTS Use Case 1 implementation (Bewohnerparken / resident parking permit), collaborating with FITKO, IM BW, Kraftfahrt-Bundesamt, and SEITENBAU on the first live implementation of the register modernization and NOOTS connection.
• Kraftfahrt-Bundesamt (Federal Motor Transport Authority)coreTechnology or IntegrationPartner in the NOOTS Use Case 1 (Bewohnerparken), providing the register that is connected to the OZG-Hub online service via NOOTS.
• Ministerium des Inneren, für Digitalisierung und Kommunen Baden-Württemberg (IM BW)coreStrategic or Co-development PartnerCo-presenter of the NOOTS Use Case 1 Best-Practice Dialogue at the Zukunftskongress 2025; strategic partner in OZG-Hub initiation and register modernization.

Scale indicators5 records

Recent moves6 records

Expansion highlights6 records

Market position

Weaknesses5 records

Competitive moat5 records

Customer concentration

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• Facebookfacebook.com/seitenbau

Revenue estimate

Valuation estimate

Number of profiles

Profiles3 records

Subsidiaries1 record

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Seitenbau