Free Browser Storage Test for LocalStorage, IndexedDB, Cache, and Quota
Run functional write/read/delete checks across common browser storage mechanisms and inspect origin quota, usage, persistence status, and secure-context availability.
Browser Storage Test for LocalStorage, IndexedDB, Cache, and Quota
| Storage mechanism | API support | Functional result | Cleanup |
|---|
Built for a complete diagnostic workflow
localStorage functional test
Browser Storage Test workflow feature designed for practical browser use.
sessionStorage functional test
Browser Storage Test workflow feature designed for practical browser use.
IndexedDB open/write/read/delete test
Browser Storage Test workflow feature designed for practical browser use.
Cache Storage functional test
Browser Storage Test workflow feature designed for practical browser use.
Storage quota estimate
Browser Storage Test workflow feature designed for practical browser use.
Current origin usage estimate
Browser Storage Test workflow feature designed for practical browser use.
Persistent-storage status
Browser Storage Test workflow feature designed for practical browser use.
Optional persistence request
Browser Storage Test workflow feature designed for practical browser use.
Secure-context reporting
Browser Storage Test workflow feature designed for practical browser use.
Per-test pass/fail matrix
Browser Storage Test workflow feature designed for practical browser use.
Origin-scoped cleanup
Browser Storage Test workflow feature designed for practical browser use.
Copyable storage diagnostic
Browser Storage Test workflow feature designed for practical browser use.
How to interpret this browser storage test
Browser storage is not a single feature. Websites may use localStorage for small synchronous key-value data, sessionStorage for tab-session state, IndexedDB for structured data, Cache Storage for request/response caching, and the Storage Manager for quota information.
This page performs small origin-scoped test writes and then removes them. A successful API existence check is not enough: the functional tests also verify that a value can be written and read back in the current browsing context.
Private browsing, storage partitioning, enterprise policies, sandboxed frames, browser settings, quota pressure, and security context can all change results. Quota and usage values are estimates and should not be treated as guaranteed free disk space.
Persistence requests are browser-controlled. Even when the API exists, the browser decides whether an origin receives persistent treatment based on its own policy and user engagement signals.
What the browser can and cannot tell you
| Signal | What it represents | How to use it |
|---|---|---|
| localStorage | Small synchronous string key/value data | Functional write/read/delete |
| sessionStorage | Tab-session scoped string data | Functional write/read/delete |
| IndexedDB | Structured asynchronous database | Database/object-store round trip |
| Cache Storage | Request/response cache | Secure-context availability may matter |
| StorageManager | Quota, usage, persistence | Values are estimates, not disk guarantees |
Build a better troubleshooting habit
Start with a baseline
Run the primary diagnostic before changing settings so you have a comparison point.
Repeat the test
One sample can be misleading. Repeat the check and compare the pattern, not only the best number.
Change one variable
When troubleshooting, change one device, browser, permission, cable, or setting at a time.
Separate browser from hardware
A browser result reflects only the parts of the input or output path that the page can observe.
Document the environment
Keep browser, operating system, device connection, scaling, or permission context with the result.
Use the next diagnostic
Open a related ready page when the result suggests a neighboring part of the device or browser stack.
Three quick questions
Finish with a quality review
Recent saved milestones on this device
Continue without a dead end
Free Browser Storage Test for LocalStorage, IndexedDB, Cache, and Quota: FAQ
Does this test show total free disk space?+
No. StorageManager reports origin-related estimates, not a guaranteed amount of free physical disk space.
Does the test leave data behind?+
The diagnostic attempts to delete its temporary keys, database, and cache after testing.
Why can an API exist but a write fail?+
Browser mode, sandboxing, permissions, quota, policy, or storage restrictions can block actual use.
What does persistent storage mean?+
It indicates whether the browser may protect an origin’s storage from routine eviction. It does not mean the data can never be removed.
Is this test the same as checking cookies?+
No. Cookies use a different mechanism. Use the cookie checker for first-party cookie behavior.
Use the result responsibly
This tool reports what a browser can observe or calculate in the current environment. Device firmware, drivers, operating-system processing, permissions, transport, display refresh, acoustic conditions, and browser implementation can add behavior that this page cannot isolate.
External technical reference: MDN: StorageManager.estimate() ↗.