Karbon APIConnect Karbon without building on its API
Karbon has a public REST API (v3) with an OpenAPI spec. Karbon customers turn on API access themselves under Settings, API Applications. Software vendors contact Karbon's partnerships team. If you're reading the docs because you need Karbon to talk to the rest of your stack, Caddi does that without you writing or maintaining integration code: you show it the job once, and it runs it across Karbon and your other tools.
- APIREST (JSON), v3
- AuthAPI key pair
- AccessSelf-serve for customers
What the Karbon API gives you
- Type
- REST (JSON), v3
- Authentication
- API key pair
- Who can get access
- Karbon customers turn on API access themselves under Settings, API Applications. Software vendors contact Karbon's partnerships team.
- What it covers
- Contacts, organizations, client groups, work items, invoices and payments, custom fields, files, budgets, time entries and webhooks.
- Limits
- Karbon recommends at most 120 requests per minute per account per API application, and list pages return up to 100 items.
Official docs: developers.karbonhq.com. Checked September 2026. Vendors change access terms, so confirm with Karbon before you build.
Building on the Karbon API vs. having Caddi run it
| The job | Build it on the API | With Caddi |
|---|---|---|
| Getting access | Register an app, get Karbon credentials, and manage tokens and refreshes. | Connect your Karbon account once. Caddi holds the connection. |
| Writing the integration | A developer maps fields, handles pagination, retries and rate limits, and writes the sync. | You show Caddi the Karbon task the way you'd train a new hire. It writes verified code for it. |
| Steps the API doesn't cover | Screens with no endpoint stay manual, or need a separate RPA tool. | Caddi uses a secure, audited browser session where there's no API, in the same automation. |
| The other systems in the loop | Each extra tool is another API, another set of credentials, another integration to own. | One automation runs across all the tools the job touches. |
| Keeping it running | Someone owns the code when the API version, fields or your process change. | Every automation is reviewed before it runs in production, and every run is logged. |
Building on the API is the right call when you have engineers and the integration is your product. When the goal is getting Karbon work off someone's desk, the build is the slow part.
What teams usually want the Karbon API for
Email & document to work item
Caddi reads inbound client email and attachments, classifies the request, and creates or updates the matching Karbon work item with the right client, assignee, and due date.
Client request chasing
Caddi tracks outstanding document requests, sends personalized reminders from the firm's template, and closes the Karbon work once everything is received.
Billing & books sync
Caddi reconciles completed Karbon work against the accounting system, drafts the invoice, and writes the matching entry back with the right client coding.
Karbon API questions
Does Karbon have an API?
Yes. Karbon has a public REST API (v3) with an OpenAPI spec, authenticated with API key pair. The official documentation is at https://developers.karbonhq.com/.
How do I get access to the Karbon API?
Karbon customers turn on API access themselves under Settings, API Applications. Software vendors contact Karbon's partnerships team.
Does the Karbon API have rate limits?
Karbon recommends at most 120 requests per minute per account per API application, and list pages return up to 100 items.
Can I connect Karbon to my other tools without writing code against its API?
Yes. With Caddi you show the Karbon task once, the way you'd train a new hire, and Caddi builds it as verified code that runs across Karbon and the other tools the job touches. Where a step has no API, Caddi uses a secure, audited browser session in the same automation.
Do I need a developer to automate Karbon with Caddi?
No. There is no integration code for you to write or maintain. Every automation Caddi builds for Karbon is reviewed before it runs in production, and every run is logged.
Connect Karbon without the build.
Drop your work email and pick a time. We'll show you Caddi running your Karbon workflow end to end.