H̊akan Källberg - Python Backend Consultant, E-Mobility

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Ladenburg, Germany

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Experience

Jan 2024 - Present

2 years 11 months

Ladenburg, Germany

Consultant

Simulina GmbH

Planning of photovoltaic systems for a citizens' initiative
Design of billing systems.

Feb 2022 - Oct 2023

1 year 9 months

Darmstadt, Germany

Consultant

Simulina GmbH

Migration of a distributed application to new hardware under Linux, Solaris and AIX
Porting of OpenSolaris tools to Linux
Use of Universal Packet Manager and EPM for packaging for various architectures
Shell script programming
Use of GitLab

Jan 2022 - Apr 2022

4 months

Königsbach-Stein, Germany

Consultant

Simulina GmbH

Development of a web application for billing charging processes at an electric vehicle charging park
Management of charging stations, users and RFID cards
Implementation with Python/Django on Raspberry Pi

Sep 2021 - Dec 2021

4 months

Weiterstadt, Germany

Consultant

Simulina GmbH

Testing of dial-in solutions in the carrier sector
Test automation with RobotFramework
Network testing with ScaPy
Use of Git, GitLab, Debian and Jira in Scrum

May 2021 - Jul 2021

3 months

Bremen, Germany

Consultant

Simulina GmbH

Porting from Python 2 to Python 3
Use of Git, GitLab and Debian in the Scrum process

Jul 2019 - Feb 2020

8 months

Vienna, Austria

Consultant

Simulina GmbH

Development of a gateway for the TALQ Smart City Protocol on a Digi Embedded Computer
Communication via the WirePas mesh network protocol and REST-based TALQ protocol
Implementation in Python3 with Twisted

Jan 2019 - Jun 2019

6 months

Stuttgart, Germany

Consultant

Simulina GmbH

Development of a REST interface for forwarding data via socket to an Unreal server
Planning of a WebSocket interface
Programming in Python
Use of Git with BitBucket and Jira

May 2018 - Oct 2018

6 months

Düsseldorf, Germany

Consultant

Simulina GmbH

Development of a QR code reader app with Python TK (tkinter)
Connection to the dcTrack backend system via a JSON-based REST interface
Packaging in Python
Analysis of QR code use cases

Jan 2018 - Mar 2018

3 months

Düsseldorf, Germany

Consultant

Simulina GmbH

API programming and design with Django REST framework
Development of an API for managing nameserver data
Evaluation of Flask, Twisted and SQLAlchemy as alternatives

Dec 2016 - Apr 2017

5 months

Frankfurt, Germany

Consultant

Simulina GmbH

Connection of mobile laptops with encrypted file systems
Installation of VS NfD systems with VPN connection
Setup of Secunet SINA workstations and SINA Smart Cards
Development of smaller Python and Bash scripts

Jan 2013 - Mar 2016

3 years 3 months

Garmisch-Partenkirchen, Germany

Consultant

Simulina GmbH

Support for the eGap research project in Garmisch-Partenkirchen in the field of electromobility
Co-development of a multi-tenant E-Mobility platform as Business-as-a-Service
Connection of charging stations via LyconSys routers using OpenVPN behind firewalls and UMTS routers
Communication via REST-based web services and integration of external geoservices
Use of Python, Bash, MySQL, PHP
Programming of charging station controls on embedded Linux devices in Python
Display of real-time charging data with Crossbar and microservices
Telephone-based activation via SIP gateway and Asterisk server

Sep 2012 - Dec 2012

4 months

Stuttgart, Germany

Consultant

Simulina GmbH

E-mail and domain administration with Postfix and Bind
Scripting in Perl, Python and Bash
Introduction of Git as a repository

Feb 2010 - Jul 2012

2 years 6 months

Schriesheim, Germany

Consultant

Simulina GmbH

Contribution to the FutureFleet research project in the field of electromobility
Development of charging management software for electric cars in Python
Web programming and data exchange with PHP and MySQL
Architecture design with REST APIs and XML/XSD, followed later by JSON interfaces

Jul 2009 - Jan 2010

7 months

Frankfurt, Germany

Consultant

Simulina GmbH

Software development on the LyconSys router platform (Embedded Linux)
Shell scripting, software packaging and web programming

May 2009 - Jun 2009

2 months

Germany

Consultant

Simulina GmbH

Development in C on AIX
Adaptation of existing RADIUS tools for IPv6

Jan 2009 - Present

17 years 11 months

Consultant

Simulina GmbH

Development of a membership management system for a sports club
Implementation of a mailing list management system in PHP/MySQL/Perl
Expansion into a multi-tenant solution

Jan 2008 - Present

18 years 11 months

Sweden

Consultant

Simulina GmbH

Set up a call center based on Asterisk

May 2007 - Apr 2009

2 years

Germany

Consultant

Simulina GmbH

Testing customer-specific DHCP and RADIUS software on AIX
Scripting and log analysis with Perl

Mar 2007 - Present

19 years 9 months

Germany

Consultant

Simulina GmbH

Set up eGroupWare with LDAP as a contact database for VoIP phones (Snom)

Jan 2007 - Feb 2007

2 months

Consultant

Simulina GmbH

Development of a call center agent application with LAMP
Perl CGI scripts for Excel export and import

Dec 2006 - Present

20 years

Consultant

Simulina GmbH

Setting up a server rack with switch, Astaro firewall, UPS, and Linux-based SAMBA/intranet server

Nov 2006 - Present

20 years 1 month

Consultant

Simulina GmbH

Installation and commissioning of an Astaro firewall with VPN connection

Oct 2006 - Present

20 years 2 months

Consultant

Simulina GmbH

Setting up a Zarafa Outlook server on Linux/MySQL

Jan 2006 - Dec 2006

1 year

Consultant

Simulina GmbH

Developing several Asterisk-based telecommunications systems worldwide

Jul 2004 - Jul 2011

7 years 1 month

Consultant

Simulina GmbH

Implementing VoIP solutions with Cisco and Asterisk VoIP servers via ISDN-PRI
Integrating IP telecommunications systems and installing VoIP phones

Mar 2004 - Present

22 years 9 months

Consultant

Simulina GmbH

Preparation and delivery of technical training in the area of s390 Linux, zSeries

Jan 2004 - Dec 2004

1 year

Consultant

Simulina GmbH

Definition and implementation of firewall, VPN, and mail concepts for the public sector and SMEs
Installation and commissioning of mail systems with SPAM-Control (SPF, Greylisting)

Jan 2003 - Dec 2004

2 years

Consultant

Simulina GmbH

Set up various web hosting services on Linux and Solaris platforms

Jan 2003 - Dec 2003

1 year

Consultant

Simulina GmbH

Worked as a webmaster for a group of brokers
Developed an automated billing system for web transactions

Jan 2002 - Present

24 years 11 months

Consultant

Simulina GmbH

Conceptual and security analysis for a trading company, including firewall consulting and installations on Linux, Solaris, and Cisco

Jan 2002 - Dec 2002

1 year

Frankfurt, Germany

Developer

Reuters AG

Modification of an application for Reuters under Solaris in C/C++
Integration of license management and additional calculation functions

Jan 2000 - Dec 2002

3 years

Developer

Telekurs AG

Development of an interface for importing security master data into the SAP Treasury System
Use of WebMethods, Perl and XML/DTD

Jan 1999 - Dec 2000

2 years

Frankfurt, Germany

Developer

Commerzbank AG

Development of a disaster recovery tool for mirroring data centers
Programming in Perl with Sybase database
Platforms: Sun E10k, Brocade SAN, EMC Symmetrix

Jan 1997 - Dec 1999

3 years

Developer

SAP/Reuters

Interface programming for SAP Treasury for real-time import of Reuters market data
Use of Solaris, C++ and Triarch SSL

Industry experience

See where this freelancer has spent most of their professional time.

Experienced in Information Technology, Retail, Telecommunication, Professional Services, Energy, and Banking and Finance.

Information Technology

Retail

Telecommunication

Professional Services

Energy

Banking and Finance

Business area experience

See which departments and functions this freelancer has contributed to most.

Experienced in Information Technology, Operations, Product Development, Customer Service, Project Management, and Finance.

Information Technology

Operations

Product Development

Customer Service

Project Management

Finance

Skills

Backend Programming
Software Engineering, Backend Programming/Scripting
Rest Apis
Interface Programming/Apis
Websockets Microservices
It Consulting
Consulting For Solar Systems And E-Mobility
Project Management
Voip - Call Centers, Pbx Systems, Asterisk
Security, Firewalls, Network Management
Mail And Web Solutions
Mail Servers/Groupware: Postfix, Egroupware, Zarafa
Client/Server And Storage Consolidation
Installation And Integration
System Administration - Focus On Networks/Linux/Solaris
Individual Training
It Experience Since: 1983
Hardware: Sun Hardware
Cisco Routers And Switches
Lyconsys Routers
Operating Systems: Linux (Especially Suse)
Solaris
Development Tools: Python ( Twisted, Django )
Microservices: Wamp/Websockets, Crossbar/Autobahn
Xml/Xsd - Json
Perl
C++ / C
Php
Simula 67
Subversion, Git, Gitlab
Databases: Mysql/Mariadb
Postgresql
Sybase
Mongodb
Database Interfaces: Python
Perl/Dbi
Sql
Odbc
Network Knowledge: Tcp/Ip
Intranet/Internet/Apache
Ethernet
Firewalls - E.G. Astaro, Ip-Filter
Snmp
Wlan, Vlan
Openvpn
Ipsec, Ipv6
Voip, Asterisk, Pbx Systems
Cisco Ios
Groupware/Crm: Egroupware, Zarafa, Owncloud, Nextcloud ...
Sugar Crm
Tcp/Ip-Based Services (Smtp/Mail - Postfix, Imap, Ftp, News, Dns, Nfs, Nis/Nis+, Samba, Www/Http, Ssh, Ssl, Voip, Etc.)
Client/Server Programming
Shell Programming (Sh, Bash, Csh/Tcsh, Ksh, Perl, Python)
Transaction Systems, Data Import, Export, Conversion
Porting And Migration Of Existing Applications To The Target Unix Platform (C/C++)
Storage, Raid, Lvm, Backup
Linux Ha
Adaptation, Extension And Enhancement Of System-Related Software
Computer-Aided Documentation Systems (Tex, Latex, Postscript, Pdf, Html, Groff, Markdown )
System V Packaging
Linux (Rpm) Packaging

Languages

German

Native

Swedish

Native

English

Advanced

Spanish

Elementary

French

Elementary

Education

Chalmers University of Technology

Physics, Computer Science · Gothenburg, Sweden

Statistics

Experience

Total positions 34

Experience in Information Technology 27 y

Avg length 5 y 10 m

Longest experience 24 y 10 m

Global experience

Countries worked in 3 (Germany, Austria, Sweden)

Primary country Germany

Expertise

Recent roles Consultant, Developer

Main industries Information Technology, Retail, Telecommunication

Main business areas Information Technology, Operations, Product Development

Member since

October 2025

Last update

October 2026

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Frequently asked questions

Have questions? Find more information here.

H̊akan is based in Ladenburg, Germany.

H̊akan speaks the following languages: German (Native), Swedish (Native), English (Advanced), Spanish (Elementary), French (Elementary).

H̊akan has at least 30 years of experience. During this time, H̊akan has worked in at least 2 different roles and for 5 different companies. The average length of individual experience is 1 year and 11 months. Note that H̊akan may not have shared all experience and actually has more experience.

Based on recent experience, H̊akan would be well-suited for roles such as: Consultant, Developer.

H̊akan's most recent position is Consultant at Simulina GmbH.

In recent years, H̊akan has worked for Simulina GmbH.

H̊akan is most experienced in industries like Information Technology, Retail, and Telecommunication. H̊akan also has some experience in Professional Services, Energy, and Banking and Finance.

H̊akan is most experienced in business areas like Information Technology, Operations, and Product Development. H̊akan also has some experience in Customer Service, Finance, and Project Management.

H̊akan has recently worked in industries like Retail, Information Technology, and Professional Services.

H̊akan has recently worked in business areas like Information Technology, Operations, and Customer Service.

H̊akan attended Chalmers University of Technology for Physics, Computer Science.

The availability of H̊akan needs to be confirmed.

Daily rate distribution

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<€800 €800-1200 €1200-1600 €1600+

The rates shown represent the typical market range for freelancers in this position based on recent contracts on our platform.

Average rates for similar positions

Rates are based on recent contracts and do not include FRATCH margin.

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Daily rate avg. 865 €

The average daily rate is the mean of all daily rates from recent contracts of comparable freelancers on our platform.

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750

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250

Median rate 800 €

The median daily rate is the middle value of all daily rates — half of comparable freelancers charge less, half charge more. Unlike the average, it is barely affected by outliers.

Calculated based on our freelancers’ daily rates as of 6 Nov 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.