API Response Headers Moving to Lowercase
Simone Carletti
on
We're upgrading our API infrastructure to Rack 3.0, which changes how HTTP response headers are formatted. Starting February 2nd, 2026, our API will return header names in lowercase.
What's Changing
HTTP response headers from our API will be returned in lowercase. For example:
Content-Typebecomescontent-typeX-RateLimit-Limitbecomesx-ratelimit-limitX-RateLimit-Remainingbecomesx-ratelimit-remaining
Why This Change
This isn't a DNSimple-specific decision, we're aligning with industry standards. RFC 7230 Section 3.2 explicitly states that HTTP header field names are case-insensitive. Rack 3.0, the web server interface powering the Rails and Hanami frameworks, and therefore our API, now returns lowercase headers by default to follow this standard.
In a perfect world, every HTTP client would already handle headers case-insensitively. However, we discovered that not all language implementations are fully aligned with this standard. Our own C# and Elixir clients needed updates, which suggests custom integrations may need review as well. That's why we're giving you advance notice.
Impact on API Clients
If you use our official API clients, most are already compliant. Two clients require updates:
All other official API clients handle header case-insensitivity correctly and require no changes.
If you have a custom integration that interacts directly with our API, review your code to ensure it handles HTTP headers case-insensitively. Any code that explicitly looks for headers like Content-Type or X-RateLimit-Limit with exact case matching will need to be updated.
Tip
If you're maintaining a custom integration, consider migrating to one of our official API clients. They're actively maintained, handle edge cases like this automatically, and will save you long-term maintenance effort.
Timeline
February 2nd, 2026: API responses will begin returning lowercase header names.
Questions?
If you have questions or need assistance reviewing your integration, please get in touch. We're happy to help ensure a smooth transition.
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Simone Carletti
Italian software developer, a PADI scuba instructor and a former professional sommelier. I make awesome code and troll Anthony for fun and profit.
We think domain management should be easy.
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