Gzip Checker
The GZIP Checker inspects whether URLs serve text assets (HTML, CSS, JavaScript, JSON, XML) with HTTP compression enabled (GZIP or…
GZIP & Brotli Compression Checker
Enter a URL to check GZIP and Brotli compression
Compression Analysis Results
Compression Details
Technical Details
Size Comparison Chart
GZIP Check History
About GZIP Compression
What is GZIP?
- • Compression: Reduces file size by 60-80%
- • Speed: Faster page loading times
- • Bandwidth: Saves server bandwidth costs
- • SEO: Improves search engine rankings
- • User Experience: Better performance
Benefits:
- • Faster website loading times
- • Reduced bandwidth usage
- • Better Core Web Vitals scores
- • Improved user experience
- • Lower hosting costs
GZIP Best Practices
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Learn more — open a section when you need details
The GZIP Checker inspects whether URLs serve text assets (HTML, CSS, JavaScript, JSON, XML) with HTTP compression enabled (GZIP or Brotli algorithms) and quantifies compression effectiveness by comparing original uncompressed sizes versus compressed response sizes, calculating compression ratios (percentage of size reduction), and measuring bandwidth savings in bytes and percentages. It performs actual HTTP requests to target URLs with Accept-Encoding headers to negotiate compression, analyzes response headers (Content-Encoding, Content-Length, Content-Type) to detect compression type and validate compression status, displays comprehensive compression statistics showing original file size, compressed size, size saved, compression percentage, and response time metrics, provides technical details including HTTP status codes, server information, content types, request timings, and response headers for troubleshooting, and generates visual compression charts comparing original, compressed, and saved data sizes for intuitive understanding of compression impact. The tool supports compression type detection (GZIP, Brotli, or no compression), validates server/CDN compression configurations, identifies compression misconfigurations or regressions, and provides exportable JSON reports and copyable text summaries for documentation, performance audits, or technical support tickets. All URL checking happens through secure proxy endpoints ensuring privacy while analyzing compression, making it ideal for validating server compression settings, verifying CDN compression configurations, spotting compression regressions after deployments, quantifying bandwidth savings for performance reporting, troubleshooting compression issues, and guiding performance improvements through data-driven compression optimization decisions.
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Enter a full URL (including http:// or https:// protocol) in the URL input field for the webpage or asset you want to check for compression, ensuring you provide complete URLs that are publicly accessible, and prepare the URL of the resource you want to analyze for compression configuration and effectiveness.
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Click the Check GZIP button or press Enter to initiate the compression analysis, watching the tool send HTTP requests with Accept-Encoding headers to negotiate compression, observe progress indicators showing compression check in progress, and wait for the tool to retrieve and analyze response data including headers and content sizes.
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Review the Compression Status card showing whether compression is Enabled (GZIP or Brotli) or Disabled, displaying compression type detected (GZIP, Brotli, or None), observing color-coded status indicators (green for enabled, red for disabled), and immediately understanding compression configuration status for the checked URL.
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Examine compression statistics including Compression Ratio percentage showing how much content was compressed (e.g., 70% means 70% size reduction), Size Saved in human-readable bytes (KB, MB) indicating bandwidth savings, Original Size showing uncompressed content size, and Compressed Size showing actual response size after compression, helping you quantify compression effectiveness and bandwidth savings.
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Open Technical Details section to view comprehensive technical information including HTTP Status Code (200, 404, etc.), Request Time showing network latency, Content Type indicating resource MIME type (text/html, text/css, application/javascript), Server information showing web server software, and Response Time metrics for performance analysis and troubleshooting compression-related issues.
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Review the Compression Chart visualization comparing original size, compressed size, and saved size using bar charts, providing visual representation of compression impact, helping you understand compression effectiveness at a glance, and enabling quick comparison of compression results across different URLs or resources.
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Export results using Copy Results button to copy formatted text summary to clipboard for documentation or reports, or click Export JSON to save comprehensive compression data including all metrics, headers, timings, and metadata in JSON format for integration into performance monitoring tools, documentation systems, or technical support tickets requiring detailed compression analysis data.
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Iterate compression optimization by checking URLs before and after server/CDN configuration changes, comparing compression results across different configurations, verifying that compression improvements are working correctly, monitoring compression status over time to detect regressions, and using compression data to guide performance optimization decisions and validate compression effectiveness after configuration updates.
Website go-live verification and CDN compression validation
Confirm Brotli or GZIP compression is enabled on CDN edges for HTML, CSS, and JavaScript assets before website launches, verify compression configurations match performance requirements, validate that critical assets (main HTML, CSS frameworks, JavaScript bundles) are properly compressed, and ensure compression settings are optimized for bandwidth savings and page load performance during go-live validation and performance verification workflows.
Incident triage and compression regression detection
Detect sudden compression disablement after deployments, configuration changes, or CDN updates that may have broken compression settings, identify compression regressions causing increased bandwidth usage, troubleshoot compression failures that impact website performance, and quickly diagnose compression-related issues during incident response and performance troubleshooting scenarios requiring rapid compression status verification.
Performance audits and bandwidth savings quantification
Quantify bandwidth savings from compression for leadership reports, calculate compression effectiveness across different asset types (HTML, CSS, JS), document compression performance improvements, and provide data-driven metrics demonstrating compression value for performance optimization initiatives, budget justifications, or technical documentation requiring compression impact analysis and savings quantification.
Server configuration validation and optimization
Verify server compression settings are correctly configured and functioning as expected, test compression levels and algorithm selection (Brotli vs GZIP), validate compression rules for different content types, and ensure server configurations deliver optimal compression ratios while maintaining acceptable compression overhead for CPU resources during server optimization and configuration validation workflows.
CDN compression policy verification and tuning
Validate CDN compression policies match requirements, verify CDN edge compression is enabled and functioning correctly, test compression across different CDN locations and edge servers, and ensure CDN compression configurations deliver expected bandwidth savings and performance improvements for global content delivery optimization requiring CDN compression validation.
Content type compression validation
Verify that text-based content types (HTML, CSS, JavaScript, JSON, XML, SVG) are compressed while binary types (images, videos, fonts) are not double-compressed, validate compression rules for different MIME types, ensure appropriate compression algorithms for different content types, and confirm compression configurations match best practices for optimal performance across various asset types requiring content-type-specific compression validation.
Performance baseline establishment and monitoring
Establish compression baselines for key assets before optimization initiatives, monitor compression effectiveness over time to detect degradation, track compression ratios across different releases or deployments, and maintain compression performance metrics for ongoing performance monitoring and optimization tracking requiring historical compression data and baseline comparisons.
Third-party service compression verification
Verify that third-party services, APIs, or external resources served through your website have proper compression enabled, check compression status of external JavaScript libraries, CSS frameworks, or API responses, and ensure third-party compression doesn't negatively impact overall website performance or bandwidth usage requiring external service compression validation and monitoring.
Prefer Brotli compression for text assets when available, as Brotli typically provides 15-20% better compression than GZIP for text content, reducing bandwidth usage further, improving page load performance, and delivering superior compression ratios while maintaining GZIP as fallback for browsers or clients that don't support Brotli compression algorithms requiring optimal compression algorithm selection.
Compress only text-based content types (HTML, CSS, JavaScript, JSON, XML, SVG, text files), as images (JPEG, PNG, GIF, WebP), videos (MP4, WebM), fonts (WOFF, WOFF2), and already-compressed formats (ZIP, GZ) use format-native compression and shouldn't be double-compressed with HTTP compression, requiring selective compression rules that target only compressible text content types for optimal performance.
Set reasonable compression levels (Brotli 5-6, GZIP 5-6) balancing compression ratio with CPU overhead, as maximum compression levels (9-11) provide minimal additional savings (2-5%) while significantly increasing CPU usage, causing server performance degradation and requiring moderate compression levels that deliver good compression ratios without excessive CPU overhead for optimal server performance and compression efficiency.
Cache compressed variants to avoid CPU-intensive real-time compression, as on-the-fly compression increases server CPU load, causes response delays, and impacts performance, requiring compressed response caching, pre-compression of static assets, or CDN edge compression that serves cached compressed content rather than compressing dynamically on each request for efficient compression delivery and reduced server load.
Lower TTL (Time To Live) values when toggling compression configurations for quicker propagation, as shorter cache TTLs enable faster distribution of compression setting changes, reduce time required for compression updates to become visible globally, and allow rapid iteration when testing compression configurations requiring quick validation of compression changes across global CDN networks or caching layers.
Test compression across different asset types to validate comprehensive compression coverage, as different content types (HTML pages, CSS stylesheets, JavaScript bundles, JSON APIs) may have different compression configurations, requiring verification that all text-based assets are properly compressed and compression rules apply consistently across all compressible content types for complete compression validation.
Monitor compression ratios over time to detect compression degradation or configuration drift, as compression effectiveness may decrease due to configuration changes, content changes, or server updates, requiring ongoing compression monitoring, ratio tracking, and alerting when compression ratios fall below expected thresholds to maintain optimal compression performance and bandwidth efficiency.
Use compression checking as part of continuous performance monitoring workflows, as regular compression validation helps identify regressions early, ensures compression remains enabled after deployments, validates compression effectiveness over time, and maintains compression performance as part of overall website performance optimization and monitoring strategies requiring systematic compression status tracking.
Attempting to compress already compressed binary formats (JPEG, MP4, ZIP files), when binary formats use format-native compression algorithms and double-compression provides minimal benefit while wasting CPU resources, causing inefficient compression application, unnecessary server overhead, and potential performance degradation, requiring compression rules that exclude already-compressed binary formats from HTTP compression.
Relying solely on origin server compression while CDN serves uncompressed content to users, when CDN configurations may disable or override origin compression, causing compression to work at origin but fail at CDN edge where users actually receive content, creating false sense of compression effectiveness and requiring CDN compression validation to ensure end-users receive compressed content from CDN edges.
Forgetting Accept-Encoding header negotiation for proxy or CDN configurations, when missing Accept-Encoding headers prevent compression negotiation, causing servers to serve uncompressed content even when compression is enabled, breaking compression functionality and requiring proper HTTP header configuration that includes Accept-Encoding negotiation for successful compression delivery.
Using maximum compression levels (Brotli 11, GZIP 9) for real-time dynamic responses causing CPU spikes, when maximum compression provides minimal additional savings (2-5%) while dramatically increasing CPU usage and response latency, causing server performance problems and requiring moderate compression levels (5-6) for dynamic content or cached compression for static content to balance compression ratio with server performance.
Not testing compression after deployments or configuration changes, when compression settings may be accidentally disabled, misconfigured, or overridden during deployments, causing unnoticed compression failures that impact performance, requiring compression validation as part of deployment verification and post-deployment testing workflows to ensure compression remains functional.
Assuming compression is enabled without verification leading to false assumptions, when compression status may change due to configuration errors, server updates, or CDN policy changes, causing unexpected bandwidth usage increases or performance degradation, requiring regular compression checking to validate actual compression status rather than assuming compression is working correctly.
Compressing content that changes frequently without caching causing excessive CPU usage, when dynamic content compression without caching increases server load significantly, requiring cached compression, pre-compression of static assets, or CDN edge compression that handles compression efficiently rather than on-the-fly compression for frequently changing content that wastes server resources.
Ignoring compression ratio trends indicating compression degradation, when decreasing compression ratios over time may indicate configuration problems, content changes affecting compressibility, or compression algorithm issues, causing missed opportunities to optimize compression and requiring compression ratio monitoring to identify and address compression effectiveness problems before they significantly impact performance.
Not considering geographic variations in compression delivery, when CDN edge servers in different regions may have different compression configurations, causing inconsistent compression across global users, requiring compression validation across multiple CDN locations to ensure consistent compression delivery worldwide and comprehensive compression verification.
Overlooking Content-Type specific compression rules causing incomplete compression coverage, when different content types may require different compression configurations or may be excluded from compression incorrectly, causing some text assets to remain uncompressed, requiring content-type-specific compression rule validation and ensuring all compressible text content types receive appropriate compression treatment.
Expecting identical compression ratios across all content types, when different content types (HTML, CSS, JavaScript) have different compressibility characteristics, causing unrealistic compression ratio expectations and requiring awareness that compression effectiveness varies by content type, structure, and redundancy levels requiring content-type-specific compression ratio understanding.
Not documenting compression configurations causing configuration drift, when lack of compression documentation leads to accidental configuration changes, inconsistent compression settings, and difficulty troubleshooting compression issues, requiring compression configuration documentation, change tracking, and systematic compression management to maintain consistent compression effectiveness over time.
The tool detects compression through Content-Encoding headers and response size analysis. Some servers or CDNs use Brotli compression (br) or other compression variants, while others may indicate compression through header variations. The tool infers compression type from headers (Content-Encoding: gzip, Content-Encoding: br) and validates compression through size comparison, displaying the detected compression algorithm (GZIP, Brotli) or compression status based on actual response analysis rather than requiring explicit "gzip" wording in status displays.
The tool checks the single URL you provide in each check. For comprehensive compression validation, run separate checks for each critical asset (main HTML page, CSS files, JavaScript bundles, API endpoints) to verify compression across different content types and paths. The tool focuses on single-URL analysis for detailed compression metrics, requiring multiple checks for complete website compression coverage and comprehensive compression validation across all critical assets.
The tool uses actual measured response sizes from HTTP requests through proxy endpoints, comparing compressed response sizes against estimated or measured original sizes. Ratios reflect real compression effectiveness based on actual HTTP responses, providing realistic compression metrics. Accuracy depends on response measurement precision, but results represent actual compression performance as experienced by browsers and users, making ratios reliable for compression analysis and optimization decision-making.
The tool processes one URL at a time for detailed analysis. For multiple URLs, run sequential checks for each URL individually. The tool maintains history of recent checks, allowing you to compare results across different URLs. For automated batch checking, consider using the exported JSON format with scripting tools, or run checks sequentially to build compression profiles across multiple assets or pages requiring comprehensive compression validation.
GZIP is the traditional compression algorithm widely supported by all browsers and servers, providing good compression ratios. Brotli is a newer algorithm offering 15-20% better compression than GZIP for text content, but requires modern browser support. Both are effective; Brotli provides better compression but GZIP has broader compatibility. Many servers support both, serving Brotli to compatible clients and GZIP as fallback for maximum compatibility and optimal compression performance.
Compression may appear disabled due to CDN overrides, proxy configurations, missing Accept-Encoding headers, content-type exclusions, file size thresholds, or server misconfigurations. CDNs may disable compression, proxy layers may strip compression headers, or server rules may exclude certain content types from compression. Check CDN settings, proxy configurations, and server compression rules to identify why compression isn't working despite configuration indicating it should be enabled.
Compression ratio shows percentage of size reduction: 70% means content was compressed to 30% of original size (70% reduction). Higher percentages indicate better compression. Typical text assets (HTML, CSS, JS) achieve 60-80% compression. Ratios below 40% may indicate inefficient compression or already-minified content. Use ratios to assess compression effectiveness and identify opportunities for compression optimization or content optimization that improves compressibility.
The tool checks publicly accessible URLs through proxy endpoints. Password-protected, authenticated, or private URLs may not be accessible for compression checking. For authenticated resources, ensure URLs are publicly accessible or use compression checking tools that support authentication. The tool focuses on publicly accessible resource compression validation for general compression analysis workflows.
Verify server compression configuration is enabled, check CDN compression settings aren't overriding server compression, validate Accept-Encoding headers are being sent correctly, ensure content types aren't excluded from compression rules, check for file size thresholds that may prevent compression, review server logs for compression errors, and test compression configuration manually. Contact server administrator or CDN support if compression configuration appears correct but compression isn't working, requiring troubleshooting to identify and resolve compression configuration issues.
Check compression after deployments, configuration changes, CDN updates, or server modifications that might affect compression. Regular monitoring (weekly or monthly) helps detect compression regressions. Include compression validation in deployment checklists and performance monitoring workflows. For critical assets, check compression more frequently to ensure optimal compression performance and catch compression issues quickly before they significantly impact website performance or bandwidth usage.
Compression typically improves performance by reducing bandwidth usage and download times, especially for text assets. Minimal CPU overhead exists for compression, but benefits usually outweigh costs. For optimal performance, use cached compression for static assets and moderate compression levels for dynamic content. Compression generally improves page load times and reduces bandwidth costs, making it essential for website performance optimization with minimal negative impact when properly configured.
Yes, the tool can check compression for any publicly accessible URL including API endpoints returning JSON, XML, or text responses. Verify API endpoints are publicly accessible (no authentication required), check that API responses are compressible text formats (not binary), and validate that API compression configurations are working correctly. API compression checking helps ensure efficient API response delivery and validates that API endpoints deliver compressed responses when appropriate for optimal API performance.