Choose Bolt
If you want to build a new JavaScript app with database options and publishing already available.
App builders
Flex vs Bolt
A new JavaScript app, or a change to the app you have?
By the Flex team
Reviewed
Which should you choose?
Choose Flex
If you want your designer to fix a confusing flow in your existing product. They can change the real screens, try them together and give engineering a change to review.
You want to improve the app your customers use. The useful result is a change to that app.
How it works
Starting a project
Bolt
Build using supported frontend technologies and a JavaScript backend. Bolt's documentation excludes Python and PHP backends.
Flex
Start a Hosted App for an internal tool, or connect the repository of the product you want to change.
Connecting data
Flex
Your engineers connect the database and decide what the app can access. Your team can then build tools using that approved data.
Reviewing changes
Flex
Your designer or product manager tries the change in a live preview. Engineering reviews the code before it goes into your product.
Publishing
Bolt
Bolt offers managed hosting. Custom-domain support is listed on Pro, while hosting allowances differ by plan.
Flex
Share your internal tool through Hosted Apps. For an existing product, use your normal release process.
Flex Hosted Apps Flex configured data access Flex product-change workflow
Maintaining it
Bolt
Keep editing the project in Bolt. Larger projects can use more tokens per request.
Flex
Come back to the same app or repository for the next change. Your engineers still review changes to product code and manage access to production data.
Pricing
Bolt
Bolt plans include tokens for building and allowances for hosting. Teams charges per member, with tokens allocated individually. Custom domains require Pro.
Flex
You pay for Flex and the AI you use. With self-hosting, you bring your own model keys and pay for the servers running your previews and apps. Your engineers set up and maintain those servers. Flex hosting takes that server work off your team.
See the linked pricing pages for current prices and plan limits.
Your code and your app
Bolt can sync code with GitHub. Flex Hosted Apps also stores source in Git. In either case, moving the code to a new host does not move the database or customer accounts.
Need an internal tool on production data?
With Hosted Apps, your team builds internal tools using production data engineering has approved. Access controls and governance are built in. You can let Flex host the environment or run it yourself.
Your engineers connect PostgreSQL or ClickHouse, supply the credentials and decide which environment an app can use. Connecting another database or service may need engineering work.
Sources
Official documentation and pricing checked on 27 September 2026. This is our view of the products, based on their documentation rather than a hands-on benchmark.