Recommended expert
Josphat (Githuka) Githuka Muthoni
Data Annotation Lead
Experience
Jan 2018 - Mar 2025
7 years 3 monthsData Annotation Lead
Sigma AI
- Lead a team of 15 annotators on large-scale computer vision projects for autonomous vehicle systems
- Developed comprehensive annotation guidelines that improved inter-annotator agreement by 35 percent
- Implemented quality control processes that reduced error rates by 42% across all projects
- Collaborated with ML engineers to identify edge cases and improve dataset quality
- Managed annotation projects for Fortune 500 clients, delivering 100% on time
Jan 2015 - Dec 2017
3 yearsData Annotation Specialist
DataWorks Inc
- Performed high-volume image segmentation and bounding box annotation for ecommerce AI systems
- Annotated text data for NLP projects including sentiment analysis and named entity recognition
- Trained new team members on annotation tools and quality standards
- Participated in guideline development and process improvement initiatives
- Maintained consistent annotation accuracy of 98.5 percent across all projects
Jan 2015 - Dec 2016
2 yearsJunior Data Annotator
Lionbridge
- Conducted image classification and tagging for facial recognition datasets
- Performed data validation and quality checks on annotated datasets
- Assisted in audio transcription and labeling for speech recognition projects
- Met daily annotation targets while maintaining high quality standards
Industries Experience
See where this freelancer has spent most of their professional time. Longer bars indicate deeper hands-on experience, while shorter ones reflect targeted or project-based work.
Experienced in Information Technology (10 years), Automotive (7 years), and Professional Services (2 years).
Information Technology
Automotive
Professional Services
Business Areas Experience
The graph below provides a cumulative view of the freelancer's experience across multiple business areas, calculated from completed and active engagements. It highlights the areas where the freelancer has most frequently contributed to planning, execution, and delivery of business outcomes.
Experienced in Quality Assurance (10 years), Project Management (7 years), and Information Technology (2 years).
Quality Assurance
Project Management
Information Technology
Summary
Data Annotation Specialist with a decade of experience in preparing, labeling, and quality-checking diverse datasets for machine learning applications. Expertise in image, text, audio, and video annotation with proven ability to develop annotation guidelines, train teams, and implement efficient workflows. Strong background in computer vision and natural language processing projects with meticulous attention to detail and deep understanding of AI/ML data requirements.
Skills
- Image, Text, Audio & Video Annotation
- Data Labeling Quality Assurance
- Annotation Guideline Development
- Team Training & Supervision
- Project Management & Workflow Optimization
- Data Analysis & Validation
- Tool: Labelbox, Cvat, Prodigy, Vgg Image Annotator, Amazon Sagemaker Ground Truth
- Technical Skills: Python, Sql, Basic Data Analysis, Microsoft Office Suite
Languages
English
AdvancedGerman
IntermediateEducation
Oct 2013 - Jun 2017
Karlsruhe University
Bachelor of Science, Computer Science · Computer Science · Karlsruhe, Germany
Certifications & licenses
Certified Data Annotation Professional (CDAP)
AWS Machine Learning Foundations
Google Cloud AI Platform Fundamentals
Profile
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Frequently asked questions
Do you have questions? Here you can find further information.
Where is Josphat based?
Josphat is based in Berlin, Germany.
What languages does Josphat speak?
Josphat speaks the following languages: English (Advanced), German (Intermediate).
How many years of experience does Josphat have?
Josphat has at least 10 years of experience. During this time, Josphat has worked in at least 3 different roles and for 3 different companies. The average length of individual experience is 3 years and 5 months. Note that Josphat may not have shared all experience and actually has more experience.
What roles would Josphat be best suited for?
Based on recent experience, Josphat would be well-suited for roles such as: Data Annotation Lead, Data Annotation Specialist, Junior Data Annotator.
What is Josphat's latest experience?
Josphat's most recent position is Data Annotation Lead at Sigma AI.
What companies has Josphat worked for in recent years?
In recent years, Josphat has worked for Sigma AI.
Which industries is Josphat most experienced in?
Josphat is most experienced in industries like Information Technology (IT), Automotive, and Professional Services.
Which business areas is Josphat most experienced in?
Josphat is most experienced in business areas like Quality Assurance (QA), Project Management, and Information Technology (IT).
Which industries has Josphat worked in recently?
Josphat has recently worked in industries like Automotive and Information Technology (IT).
Which business areas has Josphat worked in recently?
Josphat has recently worked in business areas like Project Management and Quality Assurance (QA).
What is Josphat's education?
Josphat holds a Bachelor in Computer Science from Karlsruhe University.
Does Josphat have any certificates?
Josphat has 3 certificates. These include: Certified Data Annotation Professional (CDAP), AWS Machine Learning Foundations, and Google Cloud AI Platform Fundamentals.
What is the availability of Josphat?
Josphat is immediately available full-time for suitable projects.
What is the rate of Josphat?
Josphat's rate depends on the specific project requirements. Please use the Meet button on the profile to schedule a meeting and discuss the details.
How to hire Josphat?
To hire Josphat, click the Meet button on the profile to request a meeting and discuss your project needs.
Average rates for similar positions
Rates are based on recent contracts and do not include FRATCH margin.
1200
900
600
300
Market avg: 900-1060 €
Market avg: 900-1060 €
The rates shown represent the typical market range for freelancers in this position based on recent contracts on our platform.
Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
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