IndexedDB Payload Size Estimator
Estimate IndexedDB storage usage for JSON payloads online for free. Our indexeddb payload size estimator calculates the structured clone serialization size — the actual algorithm IndexedDB uses — and shows how much LZ-String compression reduces your quota usage. Includes a four-way size comparison (structured clone, raw JSON, UTF-8, and LZ-String compressed) with a dynamic quota indicator and a ready-to-use IndexedDB code snippet. All processing happens in your browser. No signup required.
Paste any JSON payload to estimate its IndexedDB storage size using the structured clone algorithm, then compress it with LZ-String to see how much quota you save. All processing happens locally in your browser — your data never leaves your device.
Most space-efficient for string values in IndexedDB. Stores 15 bits per UTF-16 char.
Why Use Our IndexedDB Payload Size Estimator?
Accurate IndexedDB Storage Estimation
Our indexeddb payload size estimator calculates structured clone serialization size — the actual algorithm IndexedDB uses to store objects — including per-field type overhead for strings, numbers, booleans, arrays, and nested objects.
Instant LZ-String Compression for IndexedDB
Compress JSON payloads with LZ-String directly in your browser and see the exact storage savings before writing a single line of code. Our indexeddb payload size estimator shows UTF-16 and Base64 output sizes side by side.
Secure IndexedDB Payload Size Estimator Online
Your JSON payloads never leave your device. All structured clone estimation and LZ-String compression happens locally in your browser — no server upload, no cloud processing, complete privacy for sensitive application data.
IndexedDB Payload Size Estimator — No Installation
Estimate IndexedDB storage and compress payloads directly in your browser with zero software downloads, no plugins, and no account required. Works on any modern browser on any operating system.
Common Use Cases for IndexedDB Payload Size Estimator
PWA Offline Data Storage Optimization
Progressive Web Apps that cache API responses in IndexedDB benefit from LZ-String compression. Use the indexeddb payload size estimator to verify that your offline dataset fits within the device quota before shipping — especially important for low-storage mobile devices.
Browser Extension Storage Planning
Chrome and Firefox extensions use IndexedDB for persistent storage. Use the indexeddb payload size estimator to measure how much quota your extension's data model consumes and whether LZ-String compression keeps it within the browser's per-extension limits.
Client-Side Database Schema Sizing
Before implementing a client-side database with Dexie.js, PouchDB, or raw IndexedDB, use the indexeddb payload size estimator to model your object store schemas and estimate total storage requirements for a typical user's dataset.
Redux Persist & Zustand IndexedDB Adapter
State management libraries that persist to IndexedDB (redux-persist with idb-keyval, Zustand with persist middleware) can hit quota limits with large state trees. Use the indexeddb payload size estimator to measure your serialized state and decide whether LZ-String compression is needed.
QuotaExceededError Prevention
A QuotaExceededError in production is a hard crash for users. Use the indexeddb payload size estimator to proactively measure your largest payloads and add LZ-String compression before you hit the quota ceiling — especially on iOS Safari which has stricter limits.
Offline-First App Data Modeling
Offline-first apps that sync large datasets (documents, images metadata, user history) need careful storage budgeting. Use the indexeddb payload size estimator to compare raw vs compressed storage for each object store and build a realistic quota budget.
Understanding IndexedDB Storage and Compression
What is IndexedDB Payload Size Estimation?
IndexedDBis the browser's built-in NoSQL database — it stores JavaScript objects using the structured clone algorithm, which serializes each value type with specific overhead: strings as UTF-16 (2 bytes per character), numbers as 8 bytes, booleans as 1 byte, and objects/arrays with ~50 bytes of container overhead each. Our indexeddb payload size estimator calculates this structured clone size for any JSON payload, then shows how much LZ-String compression reduces the storage footprint — so you can make informed decisions about whether to compress your IndexedDB values before storing them.
How Our IndexedDB Payload Size Estimator Works
- 1Paste your JSON payload: Enter any JSON object, array, or string that you plan to store in IndexedDB. The indexeddb payload size estimator parses the JSON and calculates the structured clone size — your data never leaves your browser.
- 2Choose a storage format: Select Raw JSON (baseline), LZ-String UTF-16 (most space-efficient for string values), or LZ-String Base64 (portable, URL-safe). The indexeddb payload size estimator compresses the payload and shows the exact storage savings.
- 3Review metrics and copy the snippet: The metrics panel shows structured clone size, raw JSON size, UTF-8 size, and compressed size with visual bars — plus a ready-to-use IndexedDB code snippet for your chosen compression format.
What the Size Metrics Mean
- Structured Clone Size: The estimated bytes IndexedDB uses to store the object natively — includes per-field type overhead for strings (UTF-16), numbers (8 bytes), booleans (1 byte), and container overhead for objects and arrays.
- Raw JSON String: The byte size of
JSON.stringify(data)stored as a UTF-16 string in IndexedDB — often smaller than structured clone for deeply nested objects. - UTF-8 Bytes: The byte size if the JSON were stored as UTF-8 (e.g., in a Blob or ArrayBuffer) — useful for comparison with server-side storage.
- LZ-String Compressed: The byte size after LZ-String compression — typically 50–80% smaller than raw JSON for repetitive data structures like arrays of similar objects.
Important Limitations
The structured clone size estimate is an approximation— actual browser engine overhead varies by browser and version. Chrome's V8 and Firefox's SpiderMonkey use different internal representations. For precise measurements, use navigator.storage.estimate() before and after writing to IndexedDB in your actual application. IndexedDB quota is dynamic — typically 50% of available disk space — and varies significantly between desktop browsers, mobile browsers, and iOS Safari (which has stricter limits of ~50 MB per origin).
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Frequently Asked Questions About IndexedDB Payload Size Estimator
An IndexedDB payload size estimator calculates how much storage a JSON payload will consume in IndexedDB using the structured clone algorithm, and shows how much LZ-String compression reduces that footprint. Our free indexeddb payload size estimator online works entirely in your browser — your data is never uploaded to any server.
The estimate is accurate within ±20% for typical JSON payloads. It accounts for UTF-16 string storage (2 bytes per character), 8-byte numbers, 1-byte booleans, and ~50 bytes of container overhead per object or array. Actual browser engine overhead varies between Chrome, Firefox, and Safari. For precise measurements, use navigator.storage.estimate() in your application.
Absolutely. Our indexeddb payload size estimator processes everything locally in your browser. Your JSON payloads are never uploaded to any server, never stored, and never leave your device. This is especially important for payloads containing user data or application secrets.
Yes — 100% free, forever. No signup, no account, no premium tier, no data size limits, and no ads interrupting your workflow. Just paste your JSON, estimate, and copy the code snippet.
IndexedDB quota is dynamic — browsers typically allocate 50% of available disk space, with a minimum of ~50 MB per origin. iOS Safari has stricter limits (~50 MB per origin). Use navigator.storage.estimate() at runtime to get the exact quota and usage for the current user's device. Our tool uses a conservative 500 MB estimate for the quota bar.
Use LZ-String UTF-16 for maximum space efficiency — it stores 15 bits per UTF-16 character, making it the most compact option for string values in IndexedDB. Use Base64 if you need a portable, URL-safe format or if you're storing the compressed value in a context that doesn't support arbitrary Unicode characters.
LZ-String typically achieves 50–80% reduction on repetitive JSON data — arrays of similar objects, configuration objects with repeated keys, and user preference data compress most aggressively. Very short payloads (under 100 bytes) may not shrink due to algorithm overhead. The tool shows the exact savings for your specific data.
The LocalStorage Compression Helper focuses on the 5 MB localStorage limit and UTF-16 character count. The IndexedDB Payload Size Estimator adds structured clone size estimation — the actual algorithm IndexedDB uses — and shows a four-way size comparison (structured clone, raw JSON, UTF-8, and LZ-String compressed) with a dynamic quota indicator.
Yes. All these libraries use IndexedDB under the hood. Compress your values with LZ-String before passing them to put() or add(), and decompress when reading with get(). The tool provides a ready-to-use code snippet for the raw IndexedDB API that you can adapt for any wrapper library.