Full disclosure: we're Ryz Labs, and we're on this list. So yes, we're biased. Here's what we'd actually tell a friend, including when you should hire someone else.
The question that decides it: who runs the workloads after they move? If a provider will operate them, buy the migration from that provider. If your own team will run them, make sure your team does a lot of the migrating, with outside engineers alongside. Scale and cloud choice narrow the list from there.
Lift-and-shift is the easy part. The hard parts are the things nobody inventoried: a cron job on a forgotten VM, a hard-coded IP in a payment integration, a nightly batch that only works because two servers share a disk. The best migration partners spend real time on discovery before moving anything, and they plan cutovers with rollback steps for each wave.
Cost is the second trap. Many teams move to the cloud and find the bill is higher than the data center, because instances were sized for peak load and nothing scales down. Ask every vendor how they'll right-size, tag and track spend from the first wave, not after go-live.
The third question is the end state. Re-hosting gets you out of a data center fast. Re-platforming onto managed databases and containers, or refactoring, costs more up front but changes what you pay to run the system. Decide per application, not for the whole estate. Our cloud migration page shows how we scope waves, and our AWS vs Azure guide helps if the cloud isn't chosen yet.
Accenture reports "814k" employees and "9,000+ clients." Its cloud practice offers to "Migrate, modernize and integrate your cloud and infrastructure workloads," including "mainframe migration to the cloud." Its AWS business group claims "20k+ Certified Professionals," and it was named AWS "2025 Global Migration Consulting Partner of the Year."
Why it fits: scale and program management for estates with thousands of applications. The catch: it's built for very large programs, so a 50-server move may not be its sweet spot.
Caylent is an AWS Premier Tier Services Partner that claims "11x AWS Partner of the Year" and 850+ AWS certifications. Its services run from AWS foundations and migrations to application modernization, data modernization and cloud operations.
Why it fits: deep AWS focus, with team members across Latin America and North America. The catch: AWS only.
Slalom, founded in Seattle in 2001, offers cloud migration, modernization and optimization alongside data, AI and change work. It was named AWS's first National System Integrator Partner of the Year in the US (2021) and signed an AWS Strategic Collaboration Agreement in 2026.
Why it fits: local offices in many US cities and a consultancy that handles the people side too. The catch: you're buying a consulting engagement, so plan who runs things after.
Rackspace runs migrations in three stages: assessment, migration workshops with pilot workloads, then managed services. It holds AWS, Google Cloud and Azure partner badges and offers a packaged Rapid Migration Offer on AWS for 100+ VMs with 24x7x365 operations after.
Why it fits: one provider to move and then run your workloads across clouds. The catch: it's strongest when you want operations handed off, not kept in-house.
Mission, now part of CDW, says it will help you "Migrate from on-prem or cloud to AWS on-time and on-budget," including from Azure or Google Cloud. It claims 5,000+ AWS customer projects and offers managed services with 24/7 support afterward.
The catch: AWS only.
We provide senior cloud, DevOps and backend engineers who work on your team. They write the Terraform, move the databases, refactor the services that won't survive a lift-and-shift, and stay for the cutovers. They work US business hours, including New York hours, so a cutover at 9pm Eastern has the same people who built it. Only the top 1% of the tens of thousands of engineers we've interviewed make it, and we're trusted by Fortune 500 engineering teams.
Why we're sixth: most buyers searching for cloud migration companies want a firm to run the program, and the providers above are built for that. We fit when your team will own the result and needs senior hands now. See hire cloud engineers, AWS developers or Azure developers.
Where we're not the right fit: we provide teams, not a managed operations contract, so if you want a provider to run the workloads after the move, pick Rackspace or Mission Cloud. If you need a board-level transformation program, Accenture is built for that.
DoiT holds the AWS Migration competency and Google Cloud Migration specialization, and pairs a FinOps platform with forward-deployed cloud engineers. It claims an average 19% cloud cost reduction in the first quarter and says "we save you more than we charge." The catch: it leads with cost, so pair it with a migration team.
If you're moving thousands of applications or a mainframe, Accenture.
If you're moving to AWS and want modernization along the way, Caylent. If you then want someone to run it, Mission Cloud.
If you want one provider to migrate and operate across clouds, Rackspace.
If your own team will run the cloud and you need senior engineers on US hours to do the migration with them, we'd pick Ryz Labs. Add DoiT if cost is the worry. For old systems that need more than a move, see our legacy modernization companies list and DevOps consulting companies.
It plans and moves applications, data and infrastructure from your data center or another cloud into a new cloud, then helps you optimize or operate them.
None of the firms here publish migration prices. With us, cost is team size times duration times monthly rate: three senior engineers at $12,000 for five months comes to $180,000.
It depends on the number of applications and how much refactoring each needs. Rackspace, for example, starts with assessment and pilot workloads before moving the rest. Ask every vendor for a wave plan with dates.
Re-host when speed matters, like a data center exit. Refactor when an application will live for years and its running cost matters. Decide per application.
We checked pricing and services for every provider here in October 2026. This changes often, so double-check before you sign anything.
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