The Teams assistant demo worked on Friday. By Monday, security wanted to know who could read the SharePoint index behind it. Your Azure OpenAI deployment is aging, the board wants Claude in production by next quarter, and the vendor deck on your desk has no engineers in it. Sound familiar? Finding Claude AI development partners that can also handle Microsoft 365, Azure AI Search and MCP permissions is harder than the directories suggest. I scored each firm on Claude proof, Microsoft depth, delivery model and security.
What I Looked For
I started from a pool of roughly a dozen firms I’ve tracked that sell Claude integration or AI engineering to software companies. Then I cut hard. If a firm’s site showed no named AI delivery work, I moved on. Case studies with a concrete outcome beat logo walls every time.
I read through customer feedback on Clutch to see how clients rate these firms first-hand. I also read service pages for evidence of Azure and Microsoft 365 depth, because a Claude agent that can’t touch your tenant safely is a demo. Engagement models mattered too: who owns the model layer, the application and the cloud, or does the work get split across three vendors?
Everything below rests on public material. I haven’t hired any of these firms. Treat it as an evidence review, not a bake-off.
How They Compare
Public Clutch ratings for the five firms:
| Company | Clutch |
| Leobit | 5/5 (61 reviews) |
| Thoughtworks | – |
| Slalom | 2/5 (1 reviews) |
| Caylent | – |
| Zartis | – |
1. Leobit
Leobit has built software since 2014 and is a Certified Services Partner in the Claude Partner Network, with US headquarters in Austin and delivery centers in Lviv, Kraków, Tallinn and London. 25+ Claude-certified engineers sit in one dedicated team alongside Azure AI, .NET, Angular and DevOps engineers. One team owns prompts, tools, MCP and evaluations, plus the application and the cloud underneath.
For ACT Bermuda, Leobit built a first-line support agent in Microsoft Teams. The proof of concept was validated in four weeks, the agent moved from Azure OpenAI to Claude, and the support team’s workload dropped by 3x. Other published Claude work includes an AI sales assistant on Claude Sonnet for Tipco and a Claude Code-based development process for essencedesign. Leobit is also a Microsoft Solutions Partner for Digital & App Innovation and Data & AI, with 78 Microsoft-certified engineers, and it connects Claude to Microsoft 365, Teams, Azure AI Search and ERP systems through scoped MCP servers.
For Azure shops, Leobit is among the best anthropic partner software development companies to shortlist, because its Claude engagements are built around the Microsoft stack and ISO 27001:2022-certified security practices. On Clutch, Leobit holds 5/5 across 61 reviews. One client there described the team as a strategic partner rather than a vendor, praising its AI expertise, structured delivery and ability to run several complex initiatives at once.
Pricing sits mid-market and is billed hourly.
Every production change passes automated tests, evaluations and code review before rollout.
Best suited for: Azure and Microsoft 365 teams seeking the best anthropic partner software development companies to take Claude from proof of concept to production.
2. Thoughtworks
Founded in 1993 and headquartered in Chicago, Thoughtworks built its name on agile engineering practice and the Technology Radar it publishes twice a year. That discipline carries into AI work: evaluation, test-driven delivery and careful architecture.
The firm suits large programs where the AI feature is one piece of a bigger modernization. It brings strong consulting weight alongside the engineering. Its scale and consulting orientation also suit enterprises more than teams wanting a lean build squad.
Pricing is premium and quote-based.
Best suited for: large enterprises folding Claude work into a wider engineering transformation with heavy governance needs.
3. Slalom
The case for Slalom is breadth. Founded in 1999 in Seattle, it is a consulting firm with a long Microsoft and cloud practice, and it can staff business strategy, data and change management around an AI build.
Clutch lists Slalom at 2/5 across 1 review, a thin sample that says little either way.
Pricing is premium and quote-based.
Best suited for: business-led Microsoft programs where change management and strategy matter as much as the build.
4. Caylent
Caylent runs a cloud-native engineering model, founded in 2015 and based in Irvine, California. Its center of gravity is AWS, and its generative AI work follows that path: data pipelines, deployment, and production hardening on Amazon’s stack.
If your estate already lives on AWS, that focus is a plus. Azure-first buyers will find less to latch onto.
Pricing is premium and quote-based.
Best suited for: AWS-centered product teams that want Claude deployed on their existing cloud foundations.
5. Zartis
Zartis is a European software engineering firm that supplies dedicated engineers and project teams to product companies. Its model fits teams that want to extend their own squad instead of hand off a whole program.
Its AI work sits inside that wider engineering offer, so it is best judged on the team you would actually get.
Pricing is mid-market and hourly.
Best suited for: product companies extending an in-house team with nearshore engineers for AI features.
What to Ask Before You Sign
Which engineers hold Claude certifications, and will they be on my project? Certifications belong to people, so ask for names and roles.
Who owns the model layer and the cloud? Splitting prompts, MCP servers and Azure infrastructure across vendors creates gaps. Leobit and Thoughtworks both argue for end-to-end ownership, so test the claim.
Can you show a named Claude case study? Ask for outcomes, not logos. Slalom and Caylent have broad cloud portfolios, so press for Claude-specific examples.
How are permissions scoped? An agent reaching Microsoft 365 or ERP data needs least-privilege access and an audit trail.
What does a proof of concept look like on my own data? Four weeks is a useful benchmark.
Can the team scale to your size? A dedicated squad from Zartis or Leobit fits a product build; a company-wide program may need more headcount.
The right pick is the firm that matches your cloud, your deadline and the depth of Claude proof you demand.
Frequently Asked Questions
What do the best anthropic partner software development companies actually deliver?
They build and integrate Claude into production systems: agents inside products, assistants grounded in company documents, Claude Code adoption for engineering teams, and migrations from other models. Good partners also handle evaluations, security and ongoing support, not just the first demo.
How do I choose among the best anthropic partner software development companies for an Azure stack?
Check Microsoft partner status, named Claude case studies and how the team connects Claude to Microsoft 365, Teams and Azure AI Search. Ask who owns the cloud layer. Then compare engagement models: dedicated team, consulting program or staff augmentation.
Are there Anthropic services partners in Europe, Poland and Ukraine?
Yes. Leobit, for example, runs delivery centers in Lviv, Kraków, Tallinn and London alongside its Austin headquarters. Zartis also operates from Europe. Verify each firm’s certifications and Claude projects directly before shortlisting.
How long does a Claude proof of concept take?
Often four to eight weeks when it runs on real company data. Leobit’s ACT Bermuda proof of concept was validated in four weeks. Timelines grow with integrations, permissions and the number of source systems involved.
Is AI software development outsourcing to an Anthropic partner worth it?
It makes sense when you lack in-house experience with MCP, evaluations and Claude deployment. An outsourced team can compress the path to production, provided the contract covers testing, security review and knowledge transfer back to your engineers.
