---
description: API limits, tag key validation rules, and pagination behavior.
title: Limits and validation
image: https://developers.cloudflare.com/og-docs.png
---

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> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/resource-tagging/llms.txt  
> Use this file to discover all available pages before exploring further.

# Limits and validation

Last updated Sep 3, 2026|Copy as Markdown| [View as Markdown](https://641a99ee.previews.developers.cloudflare.com/resource-tagging/reference/limits/index.md)| [Agent setup](https://641a99ee.previews.developers.cloudflare.com/agent-setup/)

## API limits

| Limit | Value | Error code |
| --- | --- | --- |
| Maximum tags per account | 10,000 (beta) | N/A |
| Maximum tag key length | 256 characters | `1011` |
| Maximum tag value length | 1,024 characters | `1012` |
| Maximum tag filters per query | 20 | `1010` |
| Maximum OR values per filter | 10 | `1013` |
| Results per page | 100 (fixed) | N/A |

When a limit is exceeded, the API returns `400 Bad Request` with the corresponding error code.

During the beta, each account is limited to 10,000 total tags. If you need a higher limit, contact [Cloudflare support](https://641a99ee.previews.developers.cloudflare.com/support/contacting-cloudflare-support/).

## Case sensitivity

Tag keys and values are case-sensitive. `Environment`, `environment`, and `ENVIRONMENT` are treated as three distinct keys. Be consistent with casing conventions across your organization to avoid duplicate keys.

## Tag key validation

Tag keys must follow these character rules:

### Allowed

- Unicode letters (any language)
- Unicode digits (0-9)
- Underscores ( `_`)
- Periods ( `.`)
- Hyphens ( `-`)

### Not allowed

- Empty strings
- Spaces
- Special characters (except `_`, `.`, `-`)

### Examples

| Key | Valid | Reason |
| --- | --- | --- |
| `environment` | Yes | Letters only |
| `team_name` | Yes | Underscore |
| `cost-center` | Yes | Hyphen |
| `owner.email` | Yes | Period |
| `env123` | Yes | Letters and digits |
| `env name` | **No** | Contains space |
| `team@work` | **No** | Special character `@` |
| (empty) | **No** | Empty string |

Invalid tag keys return `400 Bad Request` with error code `1014`.

## Pagination

List endpoints use cursor-based pagination with a fixed page size of 100. The page size is not configurable.

Paginated endpoints:

- `GET /accounts/{account_id}/tags/keys`
- `GET /accounts/{account_id}/tags/resources`
- `GET /accounts/{account_id}/tags/values/{tag_key}`

Refer to [Filter resources by tag](https://641a99ee.previews.developers.cloudflare.com/resource-tagging/how-to/filter-resources/#pagination) for pagination examples.

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