Office Add-in Development Capabilities
Build secure, cross-platform Microsoft Office Add-ins using Office.js, modern web technologies, Microsoft 365 deployment, and AppSource publishing.
Cross-Platform Development
Build Office Add-ins for supported Microsoft 365 clients across Windows, Mac, and the web.
Explore Cross-Platform DevelopmentCentralized Deployment
Deploy and manage Office Add-ins across your organization through Microsoft 365 centralized deployment.
Explore Centralized DeploymentAppSource Publishing
From manifest validation and certification to Partner Center submission and AppSource publishing.
Explore AppSource PublishingOffice.js Development
Build modern Office Add-ins using Office.js, React, TypeScript, Microsoft Graph, and web technologies.
Explore Office.js Development
Take Your Office Add-in to AppSource
We help you publish your Office Add-in on Microsoft AppSource with support for manifest validation, Partner Center submission, certification requirements, release management, and post-launch updates, giving you a smoother path from development to marketplace release.
Proven Results in Office Add-in Development
From custom Microsoft Office Add-ins to Google Workspace extensions, we deliver secure, production-ready solutions that automate workflows, improve accuracy, and scale with your business.
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Happy ClientsTrusted by product, operations, and IT teams to solve complex workflow and integration challenges.0
Projects DeliveredSolutions delivered across Outlook, Excel, Word, PowerPoint, Microsoft 365, and Google Workspace.0
Ongoing ProjectsLong-term development partnerships focused on enhancements, support, and continuous delivery.Trusted by Businesses Worldwide
We partner with businesses to design, build, and support custom Office Add-ins for Word, Excel, Outlook, and PowerPoint. Our work spans Office.js development, Microsoft 365 integrations, workflow automation, modernization, and ongoing product support—helping teams turn complex requirements into reliable, production-ready solutions.
Reviews from Our Clients
Discover what our clients have to say about their experiences with us. At Addin Expert, we pride ourselves on delivering top-notch Office and Google add-ins tailored to meet our clients needs. Hear from our satisfied customers about their experiences and how our solutions have enhanced their productivity and efficiency.
TP
Tom Palmer
United Kindom
This guy really wants to please! He did everything perfectly and we have a very exciting and unique product. Top marks.
KH
Kieran Harland
State Library of New South Wales
Add-in Expert is the best in the business Could not recommend someone more Listened to everything I wanted but helped me build on my original idea.
TP
Tom Palmer
United Kindom
I really hope to work with this guy for a long time. absolutely wonderful service, knowledge, end product and attitude.
AD
Ashley Deverell
United States
Was good at finding solutions, what i wanted was not possible so he though along with me to come up with an alternative solution.
Hamid Boroumandian
CEO, Axya Inc.
Add-in Expert delivered his work with good quality and was very supportive throughout the whole process. He was generally available and communicated well with me and.
Mr. Stevo
United Kingdom
I had an excellent experience working with Aamir on a complex Microsoft Word add-in project. From the beginning, Aamir was communicative and highly responsive, always eager.
Matthias Hofmann
Boehmert & Boehmert
Great work by Add-in Expert. He started the work very quickly and provided an implementation that fulfills all the requirements. He was patient and polite when.
Coatesg
Australia
Add-in Expert knows his stuff. It is always a pleasure to work with professionals who care about getting the right outcome. He made every delivery within.
Milena Mitova
Digital Marketer, Speaker
Amazing experience with Add-in Expert and his team, as always. they are extremely fast, knowledgeable and most importantly focused to deliver high quality work that meets.
Christoph Drayss
Seneca Evolution UG
We collaborated with Addin Expert to create a custom Google add-on for our design team, and the results have been exceptional. Their ability to blend technical.
Bart Defour
Head of IT, Information Mapping
Add-in Expert has a strong grasp of Office.js and exhibits good communication skills. However, follow-through has been more challenging; as the project grew, keeping track of.
JF
Joseph Frantz
United States
Our business was facing a series of complex issues related to the deployment and configuration of shared runtime functionality for our Microsoft Office plug in. Junaid.
Milena Mitova
Digital Marketer, Speaker
This team always delivers. Highly recommend for React and Excel add-in work, plus anything API. Zia is phenomenal and Aamir has great customer service. Thank you!.
Soren Hartig
Cloud Future
I was a real pleasure to work with Add-in Expert, - I would hire him back any time.
Lotfi Benkhider
Scotfy SAS
Add-in Expert has good skills in Office add-in. I recommend working with him. See you soon for a new job.
Julie Tillman Taylor
United States
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
Adam New
United Kingdom
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
ashleydeverell
Netherlands
Was good at finding solutions, what i wanted was not possible so he though along with me to come up with an alternative solution.
Azaan Ali
Pakistan
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
Jvagon Zalez
Spain
He has been attentive to the changes that were emerging in scope and implementing them.
Mr. Raedgh
Jordan
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
Mr. William
United Kingdom
Add-in Expert was busy but managed to deliver the outlook add-in to scope. He was receptive to fixing issues and updates to the scope. Will work.
Tom Plamer
United Kingdom
Add-in Expert is a very reliable guy and I will continue to use him for my projects. Helpful and takes the time to understand. Would definitely.
Umair Khan
Pakistan
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
MS
Mitchel Shephard
Saber AI
Add-in Expert got to work promptly and delivered the plugin for us just before deadline. Thanks!.
BL
Bart Lieben
Belgium
It was great working with Aamir, who proved to be extremely flexible, adapting to changes in the deliverable, proactively reached out with questions. I would highly.
RT
Richard Turner
Event data Reformatter
It was a pleasure to work with Aamir on developing a new excel addin. He spent a long time ensuring that the add-in worked correctly and.
OES
Omar El-Sayed
United States
Add-in Expert is awesome. I'm a developer myself and was having issues getting an add-in published. Add-in Expert was very flexible in working with me and.
BT
Blue Tek
United States
I have really enjoyed working with Add-in Expert. He has gone above and beyond to find solutions for issues that come up and collaboratively develop an.
CE
Can Er
United States
Add-in Expert is extremely responsive and great person. Thanks for everything Add-in Expert. Man of his word.Great guy and great team.He is honest and on time.One.
RB
Roger Bonine
BEC Legal Systems
Add-in Expert was very helpful in working with us to get an Outlook add-in project started. His technical and communication skills are excellent, and he provided.
Milena Mitova
Digital Marketer, Speaker
Add-in Expert and his team are exceptional. From Chat GPT to API set up - they are great. Always having time for meetings and making sure.
TL
Tim Langley
Bavat LLC
Add-in Expert delivered the SSO plugin in time for my demo. He did a good job with communication and worked with me to get the plugin.
DB
David Bressler
United States
Very responsive and helpful in walking me thru the backend to ensure I knew exactly what the code was doing. Well commented out, as well. Always.
Milena Mitova
Digital Marketer, Speaker
Add-in Expert's team is very responsive, extremely reliable and communicates in an excellent way! If something is unclear, they prepare videos and set up live meetings.
RU
Rao Undavali
SAP
Delivered in time with good quality. Very knowledgeable. It is my 2nd project with them. Highly recommended.
Milena Mitova
Digital Marketer, Speaker
I was very impressed with Add-in Expert and his team. Their communication is excellent - from chat, to creating combined chat with my plugin developer to.
RU
Rao Undavali
SAP
We are really happy with Add-in Expert and his team. We split the project in two phases. First phase is delivered with out any issues. Second.
MN
Nick Maiorano
Doclinc technologies
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
CM
Charles Mukasa
Cyberthentic INC
Add-in Expert was a pleasure to work with. Communicated well and understood our requirement. Was very cooperative, even gave a refund, when we changed direction and.
TK
Tobias Kiesewetter
Kiesewetter GmbH & Co. KG
Add-in Expert has done a great job! I very much appreciate his contribution to out project and can highly recommend Add-in Expert. I would definitely enjoy.
TP
Tom Palmer
United Kindom
It has been a pleasure working with Add-in Expert. He understood exactly what we needed and wanted for the project, was fast at replying and implemented.
YT
Yat Tech
United States
Great solution from Add-in Expert, very accommodative on the request and revision. Throwing in some updates that really improved the end delivery! Very impressive.
DB
Data Busgmbh
Germany
Add-in Expert delivered the Proof of Concept in time and in the quality expected. We look forward to the next engagements with him.
Nils Tracy
Founder & CEO at Blinder
This was one of the best dev experiences I have had on or off of Fiverr. He did the job well and early and collaborated perfectly..
KH
Kieran Harland
United States
Excellent to deal with, work completed on time and very high standard of work. Reply’s in good time and kept me informed the entire way. Will.
Mr. Coatesg
Australia
Add-in Expert delivers exceptional work with impeccable attention to detail and bug-free results. Proactive communication and quick responsiveness made working with him a pleasure. This was.
Sargis Ghazaryan
Contractee
I had a great experience working with Add-in Expert. He was highly professional, communicated clearly, and delivered high-quality work on time. Add-in Expert was also proactive.
Nils Tracy
Founder & CEO at Blinder
He knocked it out of the park, deadlines and expectations met.
YT
David Robinson
Yat Tech
Great solution from Add-in Expert, very accommodative on the request and revision. Throwing in some updates that really improved the end delivery! Very impressive.
NW
Nywles
Netherlands
Add-in Expert worked very hard to build at Outlook plugin for us. He was very responsive and understood our needs. Great work!.
SC
Smith Caz
Indonesia
Add-in Expert is very good at implementing coding according to our wishes, besides that he explains clearly and patiently. Response speed and service are very satisfying.
TW
Mr. William
United Kingdom
Great work Add-in Expert. Thanks for your commitment to the project.
CS
Chillisign
Czech Republic
Everything went well, we recommend Add-in Expert for cooperation. đź‘Ť.
SC
Smith Caz
New York, USA
Add-in Expert is very good at implementing coding according to our wishes, besides that he explains clearly and patiently. Response speed and service are very satisfying.
TP
Tom Palmer
United Kindom
Add-in Expert is a very reliable guy and I will continue to use him for my projects. Helpful and takes the time to understand. Would definitely.
Adam New
United Kindom
Very easy to work with. Understood requirements very quickly and worked with an unfamilar database easily. Communication was excellent.
JD
Qcompany
Netherlands
Clear and good communication and wiling to think out of the box. Project scope changed during the project but this was no problem and we got.
JD
Joey Dean
United States
Great experience! Documented and executed requirements appropriately.
NS
Mr. Ntislkl
United States
Great job. Completed exactly as requested. Quick responses from seller. Will request again..
TP
Tom Palmer
United Kindom
This guy really wants to please! He did everything perfectly and we have a very exciting and unique product. Top marks.
KH
Kieran Harland
State Library of New South Wales
Add-in Expert is the best in the business Could not recommend someone more Listened to everything I wanted but helped me build on my original idea.
TP
Tom Palmer
United Kindom
I really hope to work with this guy for a long time. absolutely wonderful service, knowledge, end product and attitude.
AD
Ashley Deverell
United States
Was good at finding solutions, what i wanted was not possible so he though along with me to come up with an alternative solution.
Hamid Boroumandian
CEO, Axya Inc.
Add-in Expert delivered his work with good quality and was very supportive throughout the whole process. He was generally available and communicated well with me and.
Mr. Stevo
United Kingdom
I had an excellent experience working with Aamir on a complex Microsoft Word add-in project. From the beginning, Aamir was communicative and highly responsive, always eager.
Matthias Hofmann
Boehmert & Boehmert
Great work by Add-in Expert. He started the work very quickly and provided an implementation that fulfills all the requirements. He was patient and polite when.
Coatesg
Australia
Add-in Expert knows his stuff. It is always a pleasure to work with professionals who care about getting the right outcome. He made every delivery within.
Milena Mitova
Digital Marketer, Speaker
Amazing experience with Add-in Expert and his team, as always. they are extremely fast, knowledgeable and most importantly focused to deliver high quality work that meets.
Christoph Drayss
Seneca Evolution UG
We collaborated with Addin Expert to create a custom Google add-on for our design team, and the results have been exceptional. Their ability to blend technical.
Bart Defour
Head of IT, Information Mapping
Add-in Expert has a strong grasp of Office.js and exhibits good communication skills. However, follow-through has been more challenging; as the project grew, keeping track of.
JF
Joseph Frantz
United States
Our business was facing a series of complex issues related to the deployment and configuration of shared runtime functionality for our Microsoft Office plug in. Junaid.
Milena Mitova
Digital Marketer, Speaker
This team always delivers. Highly recommend for React and Excel add-in work, plus anything API. Zia is phenomenal and Aamir has great customer service. Thank you!.
Soren Hartig
Cloud Future
I was a real pleasure to work with Add-in Expert, - I would hire him back any time.
Lotfi Benkhider
Scotfy SAS
Add-in Expert has good skills in Office add-in. I recommend working with him. See you soon for a new job.
Julie Tillman Taylor
United States
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
Adam New
United Kingdom
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
ashleydeverell
Netherlands
Was good at finding solutions, what i wanted was not possible so he though along with me to come up with an alternative solution.
Azaan Ali
Pakistan
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
Jvagon Zalez
Spain
He has been attentive to the changes that were emerging in scope and implementing them.
Mr. Raedgh
Jordan
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
Mr. William
United Kingdom
Add-in Expert was busy but managed to deliver the outlook add-in to scope. He was receptive to fixing issues and updates to the scope. Will work.
Tom Plamer
United Kingdom
Add-in Expert is a very reliable guy and I will continue to use him for my projects. Helpful and takes the time to understand. Would definitely.
Umair Khan
Pakistan
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
MS
Mitchel Shephard
Saber AI
Add-in Expert got to work promptly and delivered the plugin for us just before deadline. Thanks!.
BL
Bart Lieben
Belgium
It was great working with Aamir, who proved to be extremely flexible, adapting to changes in the deliverable, proactively reached out with questions. I would highly.
RT
Richard Turner
Event data Reformatter
It was a pleasure to work with Aamir on developing a new excel addin. He spent a long time ensuring that the add-in worked correctly and.
OES
Omar El-Sayed
United States
Add-in Expert is awesome. I'm a developer myself and was having issues getting an add-in published. Add-in Expert was very flexible in working with me and.
BT
Blue Tek
United States
I have really enjoyed working with Add-in Expert. He has gone above and beyond to find solutions for issues that come up and collaboratively develop an.
CE
Can Er
United States
Add-in Expert is extremely responsive and great person. Thanks for everything Add-in Expert. Man of his word.Great guy and great team.He is honest and on time.One.
RB
Roger Bonine
BEC Legal Systems
Add-in Expert was very helpful in working with us to get an Outlook add-in project started. His technical and communication skills are excellent, and he provided.
Milena Mitova
Digital Marketer, Speaker
Add-in Expert and his team are exceptional. From Chat GPT to API set up - they are great. Always having time for meetings and making sure.
TL
Tim Langley
Bavat LLC
Add-in Expert delivered the SSO plugin in time for my demo. He did a good job with communication and worked with me to get the plugin.
DB
David Bressler
United States
Very responsive and helpful in walking me thru the backend to ensure I knew exactly what the code was doing. Well commented out, as well. Always.
Milena Mitova
Digital Marketer, Speaker
Add-in Expert's team is very responsive, extremely reliable and communicates in an excellent way! If something is unclear, they prepare videos and set up live meetings.
RU
Rao Undavali
SAP
Delivered in time with good quality. Very knowledgeable. It is my 2nd project with them. Highly recommended.
Milena Mitova
Digital Marketer, Speaker
I was very impressed with Add-in Expert and his team. Their communication is excellent - from chat, to creating combined chat with my plugin developer to.
RU
Rao Undavali
SAP
We are really happy with Add-in Expert and his team. We split the project in two phases. First phase is delivered with out any issues. Second.
MN
Nick Maiorano
Doclinc technologies
We were looking for an expert on Microsoft Outlook platform and Add-in Expert knows it very well. Not only was he able to implement our Outlook.
CM
Charles Mukasa
Cyberthentic INC
Add-in Expert was a pleasure to work with. Communicated well and understood our requirement. Was very cooperative, even gave a refund, when we changed direction and.
TK
Tobias Kiesewetter
Kiesewetter GmbH & Co. KG
Add-in Expert has done a great job! I very much appreciate his contribution to out project and can highly recommend Add-in Expert. I would definitely enjoy.
TP
Tom Palmer
United Kindom
It has been a pleasure working with Add-in Expert. He understood exactly what we needed and wanted for the project, was fast at replying and implemented.
YT
Yat Tech
United States
Great solution from Add-in Expert, very accommodative on the request and revision. Throwing in some updates that really improved the end delivery! Very impressive.
DB
Data Busgmbh
Germany
Add-in Expert delivered the Proof of Concept in time and in the quality expected. We look forward to the next engagements with him.
Nils Tracy
Founder & CEO at Blinder
This was one of the best dev experiences I have had on or off of Fiverr. He did the job well and early and collaborated perfectly..
KH
Kieran Harland
United States
Excellent to deal with, work completed on time and very high standard of work. Reply’s in good time and kept me informed the entire way. Will.
Mr. Coatesg
Australia
Add-in Expert delivers exceptional work with impeccable attention to detail and bug-free results. Proactive communication and quick responsiveness made working with him a pleasure. This was.
Sargis Ghazaryan
Contractee
I had a great experience working with Add-in Expert. He was highly professional, communicated clearly, and delivered high-quality work on time. Add-in Expert was also proactive.
Nils Tracy
Founder & CEO at Blinder
He knocked it out of the park, deadlines and expectations met.
YT
David Robinson
Yat Tech
Great solution from Add-in Expert, very accommodative on the request and revision. Throwing in some updates that really improved the end delivery! Very impressive.
NW
Nywles
Netherlands
Add-in Expert worked very hard to build at Outlook plugin for us. He was very responsive and understood our needs. Great work!.
SC
Smith Caz
Indonesia
Add-in Expert is very good at implementing coding according to our wishes, besides that he explains clearly and patiently. Response speed and service are very satisfying.
TW
Mr. William
United Kingdom
Great work Add-in Expert. Thanks for your commitment to the project.
CS
Chillisign
Czech Republic
Everything went well, we recommend Add-in Expert for cooperation. đź‘Ť.
SC
Smith Caz
New York, USA
Add-in Expert is very good at implementing coding according to our wishes, besides that he explains clearly and patiently. Response speed and service are very satisfying.
TP
Tom Palmer
United Kindom
Add-in Expert is a very reliable guy and I will continue to use him for my projects. Helpful and takes the time to understand. Would definitely.
Adam New
United Kindom
Very easy to work with. Understood requirements very quickly and worked with an unfamilar database easily. Communication was excellent.
JD
Qcompany
Netherlands
Clear and good communication and wiling to think out of the box. Project scope changed during the project but this was no problem and we got.
JD
Joey Dean
United States
Great experience! Documented and executed requirements appropriately.
NS
Mr. Ntislkl
United States
Great job. Completed exactly as requested. Quick responses from seller. Will request again..
TP
Tom Palmer
United Kindom
This guy really wants to please! He did everything perfectly and we have a very exciting and unique product. Top marks.
KH
Kieran Harland
State Library of New South Wales
Add-in Expert is the best in the business Could not recommend someone more Listened to everything I wanted but helped me build on my original idea.
TP
Tom Palmer
United Kindom
I really hope to work with this guy for a long time. absolutely wonderful service, knowledge, end product and attitude.
AD
Ashley Deverell
United States
Was good at finding solutions, what i wanted was not possible so he though along with me to come up with an alternative solution.