Flags Endpoint

Get all flags

Fetches the complete flag configuration for the authenticated environment. SDKs typically call this once during initialization and then keep the data in memory.

GET /flags

Response

{
  "environment": "env-abc123",
  "version": 42,
  "flags": [
    {
      "key": "dark-mode",
      "version": 3,
      "type": "Boolean",
      "enabled": true,
      "variations": [
        { "key": "on", "value": true },
        { "key": "off", "value": false }
      ],
      "rules": [
        {
          "id": "rule-abc123",
          "priority": 0,
          "conditionGroups": [
            {
              "operator": "Or",
              "conditions": [
                { "attribute": "country", "operator": "In", "values": ["US", "CA"], "negate": false },
                { "attribute": "email", "operator": "EndsWith", "values": ["@example.com"], "negate": false }
              ]
            },
            {
              "operator": "And",
              "conditions": [
                { "attribute": "plan", "operator": "Equals", "values": ["pro"], "negate": false }
              ]
            }
          ],
          "serve": {
            "type": "Fixed",
            "variation": "on"
          }
        }
      ],
      "fallthrough": {
        "type": "Fixed",
        "variation": "off"
      },
      "offVariation": "off",
      "prerequisites": [
        { "prerequisiteFlagKey": "new-theme-engine", "expectedVariationKey": "on" }
      ],
      "clientSideVisible": true
    }
  ],
  "segments": [
    {
      "key": "beta-testers",
      "version": 1,
      "conditions": [
        {
          "attribute": "plan",
          "operator": "In",
          "values": ["pro", "enterprise"],
          "negate": false
        }
      ],
      "conditionLogic": "And"
    }
  ]
}

Response fields

Field	Type	Description
environment	string	Environment identifier for the SDK key
version	int	Configuration version (increments on any change)
flags	FlagDto[]	All flags in this environment
segments	SegmentDto[]	All segments (referenced by targeting rules)

---

Get a single flag

Fetches the configuration for one flag by its key.

GET /flags/{key}

Path parameters

Parameter	Type	Description
key	string	The flag key

Response

Returns a single FlagDto object (see data types below). Returns 404 if the flag does not exist.

---

Data types

FlagDto

Field	Type	Description
key	string	Unique flag identifier
version	int	Flag configuration version
type	string	"Boolean", "String", "Number", or "Json"
enabled	bool	Whether the flag is on in this environment
variations	VariationDto[]	All possible return values
rules	RuleDto[]	Targeting rules, evaluated in priority order
fallthrough	ServeConfigDto	What to serve when the flag is on and no rules match
offVariation	string	Variation key returned when the flag is off
prerequisites	PrerequisiteDto[]	Flags that must serve a given variation before this flag’s rules run. Empty when the flag has none
clientSideVisible	bool	Whether client-side SDKs may receive this flag. The Cloudflare Workers SDK reads it to decide which flags bootstrapValues returns

VariationDto

Field	Type	Description
key	string	Variation identifier
value	any	The value (boolean, string, number, or JSON object)

PrerequisiteDto

Field	Type	Description
prerequisiteFlagKey	string	Key of the flag this one depends on
expectedVariationKey	string	Variation the prerequisite flag must serve

Prerequisites are checked in order, after enabled and before any rule, against the same context. If one of those flags serves anything other than its expectedVariationKey, this flag serves its offVariation and no rule runs. A prerequisite can have prerequisites of its own. See Prerequisites for how to set them up.

RuleDto

Field	Type	Description
id	string	Rule identifier
priority	int	Execution order (lower = evaluated first)
conditionGroups	ConditionGroupDto[]	Groups of conditions. The rule matches when every group matches
serve	ServeConfigDto	What to serve if the rule matches
segmentKey	string?	Segment key if the rule targets a segment. Omitted otherwise

ConditionGroupDto

Field	Type	Description
operator	string	"And" (every condition in the group must match) or "Or" (any one is enough)
conditions	ConditionDto[]	The conditions in this group

Groups are ANDed together, and each group’s operator applies only to the conditions inside it. The example rule needs plan to equal pro, plus at least one of the two conditions in the first group: a country of US or CA, or an email ending in @example.com. A rule with an empty conditionGroups list matches every context.

When segmentKey is set, the segment’s own conditions and conditionLogic decide the match, and the rule’s conditionGroups are not read. Segments keep that flat shape (see SegmentDto below).

ConditionDto

Field	Type	Description
attribute	string	Context attribute to check (e.g., "user_id", "country")
operator	string	Comparison operator (see below)
values	string[]	Values to compare against
negate	bool	Invert the condition result

Condition operators: Equals, NotEquals, Contains, NotContains, StartsWith, EndsWith, In, NotIn, MatchesRegex, GreaterThan, LessThan, GreaterThanOrEqual, LessThanOrEqual, Before, After, SemverEquals, SemverGreaterThan, SemverGreaterThanOrEqual, SemverLessThan, SemverLessThanOrEqual

ServeConfigDto

Field	Type	Description
type	string	"Fixed" or "Rollout"
variation	string?	Variation key (when type is Fixed)
bucketBy	string?	Attribute to hash for rollout bucketing
salt	string?	Hash salt for consistent bucketing
variations	WeightedVariationDto[]?	Weighted variations (when type is Rollout)

WeightedVariationDto

Field	Type	Description
key	string	Variation identifier
weight	int	Percentage weight (0—100, must sum to 100 across all entries)

SegmentDto

Field	Type	Description
key	string	Segment identifier
version	int	Configuration version
conditions	ConditionDto[]	Conditions that define segment membership
conditionLogic	string	"And" or "Or"

See also

• API Overview — authentication, rate limiting, and all endpoints
• Evaluate Endpoint — evaluate flags for user contexts
• Streaming Endpoint — receive real-time flag.updated events
• Targeting & Segments — understand rules, conditions, and segments
• SDK Overview — official SDKs fetch and cache flags automatically