Supported Worker API behavior is tracked against Workers runtime APIs. The differences below come from single-node topology and the pinned workerd. Cloudflare products that are not provided: Unsupported.
| Topic |
Behavior |
Docs |
Outbound fetch / sockets / node:net / node:tls |
Shared native workerd Network(allow=["network","local"], deny=["unix","unix-abstract"]); host-routable public, private, loopback, link-local, and metadata IPs are reachable |
TCP sockets |
Named Service/DO Fetcher.connect |
Declared capability tunnel, not a second general outbound |
|
| CF IP-range block / self-connect detector / SMTP 25 |
Not provided |
|
| Runtime / binding-backend / workerd-internal listeners |
Loopback |
|
| Control / data listeners |
Default loopback; an operator may expose them |
|
| Destination filtering, network isolation, ingress, and SMTP egress policy |
Operator-owned through the host firewall, namespace, container, or VM |
|
| Request-scoped CPU / subrequest / simultaneous-connection quotas |
The pinned workerd standalone process does not enforce them yet |
Limits |
LimitEnforcer subrequest accounting |
No-op; getLimitsExceeded() always reports none |
|
Explicit Dynamic Worker limits |
Rejected natively, including an empty object; default CPU/memory/subrequest enforcement belongs to W2 |
Bindings |
| Unix-socket denial, product durable limits, handle cleanup, process supervision |
Still apply |
|
| Other numeric ceilings |
Limits |
|
| Deploy authority |
One local SQLite authority and one supervised runtime generation |
Versions and deployments |
| Global rollout / placement / traffic splitting / account management / billing control plane |
Not provided |
|
| Static Assets |
Immutable deployment content on the selected Local/S3 authority; routing and bindings covered |
Static Assets |
| Global CDN placement / replication / purge propagation / product quotas |
Not provided |
|
| Service Bindings |
Default / named fetch and RPC within one platform authority |
Bindings |
| Cross-region placement / global service discovery |
Not provided |
|
| Target admission, deployment pins, capability lifetime, recovery |
Local and fail closed |
|
| Cron |
UTC only, five fields, plus documented local Quartz-like extensions |
Cron Triggers |
| Cron recovery |
At most the newest slot within misfire grace; no full downtime replay |
|
| Cron known failures |
Configured bounded local retry unless noRetry() is called |
|
| Cron unknown dispatch |
Consumes a delivery attempt; retries only within budget and a fixed 15-minute deadline |
|
| Topic |
Behavior |
Docs |
| KV topology |
Single-node SQLite authority; no global replication or edge-cache propagation timing |
KV |
| R2 |
Object bytes held by the selected single-node Local or S3-compatible authority |
R2 |
| R2 global placement / replication |
Not provided |
|
| D1 topology |
Single local-primary SQLite authority |
D1 |
| D1 read-replica / region routing |
Not provided |
|
D1 served_by / region / colo metadata / billing counters |
Not provided |
|
| D1 bookmarks |
Opaque bookmarks preserve same-database local sequential visibility |
|
D1 rows_read / rows_written |
Stable local SQLite execution counters |
|
D1 dump() |
Current hosted non-alpha dump() is rejected |
|
| Topic |
Behavior |
Docs |
| Durable Object placement |
Placed on the owning instance’s local workerd process |
Durable Objects |
| Location hints / jurisdiction / global migration |
No geographic scheduling effect |
|
| Queues durability |
Single-node scheduler.sqlite; at-least-once delivery |
Queues |
| Queues global FIFO |
Not provided |
|
| Queues unknown native dispatch |
Retains lease and does not consume tenant retry budget; later delivery can repeat the same attempt number |
|
| Workflows execution |
Local SQLite authority |
Workflows |
| Workflows callbacks |
At-least-once until result commits; replay skips durably completed callbacks |
|
| Workflows external effects |
Do not roll back with Workflow snapshots |
|
| Workflows cross-region execution / global placement / dashboard / observability |
Not provided |
|
| Topic |
Behavior |
Docs |
| Cache authority |
Workers Cache and Cache API are single-node local authority |
Workers Cache, Cache API |
| Automatic caching |
Requires explicit s-maxage or max-age |
|
| Heuristic TTL / global replication / purge propagation |
Not provided |
|
| Tiered cache / Cache Rules / Cache Deception Armor / plan-dependent behavior |
Not provided |
|
| Default object size |
16 MiB per cached object; 1 GiB logical body bytes per Worker |
|
| Live values |
ocd capabilities --json; see Limits |
|
| Images |
Bounded local raster transform binding, not hosted Cloudflare Images |
Images |
| Hosted delivery / upload / signing, URL transforms, video, AI upscale, product quotas |
Out of scope |
|
open-compute:manual AI Search is an explicit API superset, not a compatibility deviation. Only open-compute:ai-search types and the namespaced openComputeCreateManual / openComputeUpsert methods expose it. Official Cloudflare management routes, source enums, item shapes, and conformance counts remain unchanged.
Local native extensions ([extensions.<name>], facade-only HOST, OCH1/OCP2 Provider attach) are likewise an open-compute superset. They are not Cloudflare hosted Worker capabilities and are not counted in the Worker API inventory. See Extensions.
