The Capture Website Performance API allows developers and businesses to instantly evaluate the technical performance of any web page by simply providing its URL. Based on advanced metrics and real-time analysis, this API provides accurate information about how efficiently a site loads, executes scripts, and manages layout stability. By returning structured diagnostic data, it helps identify performance bottlenecks, JavaScript execution overloads, caching inefficiencies, and cumulative layout shifts that can negatively impact the user experience.
When a request is made, the API generates a comprehensive performance audit that includes key metrics such as startup time, CPU usage, script parsing and compilation duration, and total JavaScript execution time. It also evaluates caching efficiency to determine whether assets are served with optimal lifetime, and provides details on layout shifts to assess visual stability during page load. The API reports the number of scripts, fonts, and requests made by the web page, as well as metrics such as total block time (TBT), cumulative layout shift (CLS), and first contentful paint (FCP).
Essentially, the Capture Website Performance API acts as an automated digital performance auditor. It helps you identify where resources are being wasted, where rendering delays occur, and how to prioritize critical requests. Whether you manage large-scale websites or individual landing pages, this API provides the transparency and actionable data needed to maintain top-notch web performance, improve SEO rankings, and ensure a smooth browsing experience across all devices.
Analyze the web performance of any URL, detect JavaScript execution time, caching, and recommended optimizations to improve speed and efficiency.
Perfomance Information - Endpoint Features
| Object | Description |
|---|---|
url |
[Required] |
{"cached":true,"ok":true,"raw":{"analysisUTCTimestamp":"2026-03-27T22:56:41.424Z","captchaResult":"CAPTCHA_NOT_NEEDED","id":"https://www.google.com/","kind":"pagespeedonline#result","lighthouseResult":{"audits":{"bootup-time":{"description":"Consider reducing the time spent parsing, compiling, and executing JS. You may find delivering smaller JS payloads helps with this. [Learn how to reduce Javascript execution time](https://developer.chrome.com/docs/lighthouse/performance/bootup-time/).","details":{"headings":[{"key":"url","label":"URL","valueType":"url"},{"granularity":1,"key":"total","label":"Total CPU Time","valueType":"ms"},{"granularity":1,"key":"scripting","label":"Script Evaluation","valueType":"ms"},{"granularity":1,"key":"scriptParseCompile","label":"Script Parse","valueType":"ms"}],"items":[{"scriptParseCompile":128.51639999999998,"scripting":245.60880000000108,"total":395.382000000001,"url":"https://www.google.com/xjs/_/js/k=xjs.hm.en.R1dbi_UucrM.2019.O/am=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAQAAEAACAAAAAAAABAAAAAAAAAAAAAAAAAACUQAAAAAAAAAAAAwAAAAABAAAAAAAAAMAAQAAAQQAQABMAAAAAAAAAAAAAAAAAAAAAAQRCAAgAAA8A8AIwAAAAAAgAQAgAWgAQAAAAIIAAAAAACAAAAABAAAAQAAAAAAAAAAAAEAAAAAAAAQAICgAAAAAAIAAAAAAEAAAAAAAAAAAAAAAAAAAACAASAAAAAAAAAAAAAAAIADABAIAAAAADiIMAIAgAAAAAAAGgAeCAwRFAAAAAAAAAAAAAAAAAAAAAAAAA5ggDMIIAAEAAAAAAAAAAAAAAAAAAAAAAAAAABICLoEAAAAAAAMAg/d=1/ed=1/dg=4/br=1/rs=ACT90oFw2GBdzwhugOAAHz8v0roCgNijKA/ee=ALeJib:B8gLwd;AfeaP:TkrAjf;BMxAGc:E5bFse;BgS6mb:fidj5d;BjwMce:cXX2Wb;CIZTGb:Kqhykb;CxXAWb:YyRLvc;DQEued:Fevhcf;DULqB:RKfG5c;Dkk6ge:JZmW9e;DpcR3d:zL72xf;Du7NI:C6zLgf;EABSZ:MXZt9d;EVNhjf:pw70Gc;EjXHpb:pSHqh;EmZ2Bf:zr1jrb;EnlcNd:WeHg4;F54IAe:ZgsFh;F9mqte:rlHKFc;FSxmUe:fiZR8b;Fkukfc:i8H2c;Fmv9Nc:O1Tzwc;G0KhTb:LIaoZ;GEkGdd:e1RzQd;GleZL:J1A7Od;HMDDWe:G8QUdb;HgsCtf:jLgnvd;IBADCc:RYquRb;IoGlCf:b5lhvb;JXJSm:ii1RGf;JXS8fb:k0T3Ub;JqSq7d:y9ePhe;JsbNhc:Xd8iUd;K5nYTd:ZDZcre;KA3P2:C3JnCe;KDb6nb:fE9n2;KOxcK:OZqGte;KQzWid:ZMKkN;KpRAue:Tia57b;LBgRLc:SdcwHb,XVMNvd;LBn8Cf:bJ9L0c;LEikZe:byfTOb,lsjVmc;LXA8b:q7OdKd;LsNahb:ucGLNb;NJ1rfe:qTnoBf;NPKaK:SdcwHb;NSEoX:lazG7b;Np8Qkd:Dpx6qc;Nyt6ic:jn2sGd;OIfWUb:qfOYcd;OgagBe:cNTe0;OiqE2c:TFpEK;OoK5v:Sp69O;OohIYe:mpEAQb;Pjplud:PoEs9b;PpTLXd:pJYjx;Q1Ow7b:x5CSu;QE20Be:gIltO;QFOGlf:PQ2Aoe;QGR0gd:Mlhmy;QYLF2b:pAQYUd;Qw8Feb:jpavUe;R4IIIb:QWfeKf;R9Ulx:CR7Ufe;RCF5Sd:X1kBmd;SLtqO:Kh1xYe;SMDL4c:fTfGO;SNUn3:ZwDk9d,xD8Kp;ScI3Yc:e7Hzgb,e7Hzgb;ShpF6e:N0pvGc;SwCqAd:fXbCZc;SzQQ3e:dNhofb;TIUVQd:M8uRWb;TroZ1d:vVVzjb;U96pRd:FsR04;UBKJZ:LGDJGb;UDrY1c:N0F29d,W50NVd,eps46d,rw5jGd,wciyUe;UVmjEd:EesRsb;UVzb9c:IvPZ6d;UYRIEb:HzTAQc;UyG7Kb:wQd0G;V2HTTe:RolTY;VGRfx:VFqbr;VMuEm:pL7sBc;VN6jIc:ddQyuf;VOcgDe:YquhTb;VhA7bd:vAmQFf;VsAqSb:PGf2Re;WDGyFe:jcVOxd;WXtNeb:QU9BMd;Wfmdue:g3MJlb;Y3c5sd:FGbfLe;YIZmRd:A1yn5d;YV5bee:IvPZ6d;YnHUBf:sNsSob;ZSH6tc:QAvyLe;ZWEUA:afR4Cf;ZlOOMb:P0I0Ec;a56pNe:JEfCwb;aAJE9c:WHW6Ef;aCJ9tf:qKftvc;aVZq3e:EMeVIb;aZ61od:arTwJ;aci7y:Z5Tr6c;bDXwRe:UsyOtc;bUIkwb:WMwEHe;bcPXSc:gSZLJb;cEt90b:ws9Tlc;cFTWae:gT8qnd;dIoSBb:ZgGg9b;dLlj2:Qqt3Gf;dXdZV:a7QTqd;dowIGb:ebZ3mb,ebZ3mb;dtl0hd:lLQWFe;eBAeSb:Ck63tb;eBZ5Nd:audvde;eHDfl:ofjVkb;eJKchc:ATg1be;eO3lse:UefOmb;euOXY:OZjbQ;g8nkx:U4MzKc;gaub4:TN6bMe;gtVSi:ekUOYd;h3MYod:ws9Tlc;hK67qb:QWEO5b;hVic1b:Kqhykb;heHB1:sFczq;hjRo6e:F62sG;hlqGX:FWz1ic;hsLsYc:Vl118;hwoVHd:zw4U8c;iFQyKf:QIhFr;iySzae:a6xXfd;jJj2G:kF2o2b;k1O0rf:pnOULd;k2Qxcb:XY51pe;kbAm9d:MkHyGd;lOO0Vd:OTA3Ae;lbfkyf:MqGdUd;liAz7d:kF2o2b;lkq0A:JyBE3e;mWzs9c:fz5ukf;nBZnZe:CvErjb;nJw4Gd:dPFZH;nrDcw:SuEoDe;oGtAuc:sOXFj;oSUNyd:fTfGO,fTfGO;oUlnpc:BO43gd;okUaUd:wItadb;pKJiXd:VCenhc;pNsl2d:j9Yuyc;pXdRYb:JKoKVe;pj82le:ww04Df;qGV2uc:HHi04c;qQEoOc:KUM7Z,d7YSfd;qZx2Fc:j0xrE;qaS3gd:yiLg6e;qafBPd:sgY6Zb;qavrXe:I0C9u;qddgKe:d7YSfd,x4FYXe;rmWaj:PMS6Sd;ropkZ:UT1DG;sTsDMc:kHVSUb;sZmdvc:rdGEfc;tH4IIe:Ymry6;teSRSb:BMLai;tosKvd:ZCqP3;trZL0b:qY8PFe;uuQkY:u2V3ud;vEYCNb:FaqsVd;vRlMvf:Iw9Xo;vfVwPd:lcrkwe;w3bZCb:ZPGaIb;w4rSdf:XKiZ9;w9w86d:dt4g2b;wQlYve:aLUfP;wR5FRb:O1Gjze,TtcOte;wV5Pjc:L8KGxe;x9N9ie:KH4Qof;xBbsrc:NEW1Qc;ysNiMc:CpIBjd;yxTchf:KUM7Z;z97YGf:oug9te;zOsCQe:Ko78Df;zaIgPb:Sl0pxd/m=bct,cdos,hsm,jsa,qim,rr4R9e,cEt90b,SNUn3,qddgKe,sTsDMc,dtl0hd,eHDfl,YV5bee,d,csi"},{"scriptParseCompile":14.461199999999993,"scripting":42.693600000000046,"total":125.01120000000002,"url":"https://www.google.com/"},{"scriptParseCompile":32.58,"scripting":63.69239999999999,"total":107.04839999999999,"url":"https://www.google.com/xjs/_/js/k=xjs.hm.en.R1dbi_UucrM.2019.O/ck=xjs.hm.wNziNeVO56g.L.B1.O/am=ACBAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAIAAAAAEQAQAIEACCAAAAAAAAxAAEAUAAAAAAAACAAAACUQAAAAgAAAAAAAwAAAAABAAAAAAAAAMAAwAAAQQAQABMAAAAAAAAAACAAAAAAAAAAAQRCAAgAAA8A8AIwAAAAAAg8QAgAWgAQAAAAIIAxAAAgCEUAgQBAEAAQBAAAAAAAAAAAEAAAAAAAAQAICgQAAAAAIAAAAAAEAAAAgAAF1HDAAAABggABCAgSAAEAAAABAAAAAAAIALABAIAABgADiIMAIAgAAAAAAAGgAeCAwRFAAAAAAAAAAAAAAAAAAAAAAAAA5ggDMIIAAEAAAAAAAAAAAAAAAAAAAAAAAAAABICLoEAAAAAAAMAg/d=0/dg=0/br=1/ujg=1/rs=ACT90oGCygK1GOmBrae16F-jvLjYKB3hVg/m=U9EYge,sy1s3,loL8vb,sy1s4,sy1rz,sy1b3,syzt,syzw,syzv,sygb,syzs,syzu,syzk,syzn,sy10d,syuw,syff,sy109,sycw,sycx,sycs,sy10g,syga,sy10c,sy10h,sy10f,sy10e,sy10i,syzr,syzy,syzi,sy108,sy100,sy105,sy101,syv4,syv3,syzz,sy104,syzj,syz9,syw1,syw0,syzl,ms4mZb,sy1pm,HoZvlf,sy1qn,eT8Xz,syfa,syf9,mI3LFb,syfg,lazG7b,sytb,xRxDld,syfw,Wq6lxf,sytr,sytq,syto,sypf,syk3,syh6,syl1,syk4,syk7,syjt,syju,syh9,syha,syi0,syhr,syh5,syh4,syh7,sypg,OZLguc,sy1ax,sytx,syrr,syp2,syrs,Mbif2,ipWLfe,sy1az,QVaUhf,sy8k,sy8j,sygt,sygs,sygq,sygp,sygy,sygw,sygo,sycv,syc7,sybt,syc6,syby,syc1,sybx,sybm,sybv,syc4,sybu,sybf,sybh,syct,sycm,sych,sycf,sycl,syci,sybo,sybp,sybq,sybr,sybn,sybs,syd0,sybi,syb5,sybd,syav,syb3,sybc,sybl,sycj,sygj,sygn,sy91,sy8x,sy90,sygl,sygk,sygi,sygf,sygd,sy95,uxMpU,syg3,syd4,syd3,syco,sycn,syd7,sybk,sycc,syd2,syda,sy9o,sy9l,sy9k,sy9j,sy9i,sy9h,Mlhmy,QGR0gd,PoEs9b,Pjplud,OTA3Ae,sy9e,A1yn5d,YIZmRd,sy8t,sy8r,sy8q,sy8p,sy8n,byfTOb,lsjVmc,LEikZe,sy8m,kWgXee,ovKuLd,sgY6Zb,qafBPd,ebZ3mb,dowIGb,sy1b2,sy1b1,sy1b0,SJpD2c,sy1kp,sy1jt,EgWzsb,sy1kr,sy1kq,syw3,YHnUBc,sy1qr,L3vX2d,sy1qq,KWMuje,sy1qt,syxu,sy1qs,syxv?xjs=s3"},{"scriptParseCompile":29.081999999999997,"scripting":58.66440000000007,"total":93.52200000000006,"url":"https://www.google.com/xjs/_/js/k=xjs.hm.en.R1dbi_UucrM.2019.O/am=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAQAAEAACAAAAAAAABAAAAAAAAAAAAAAAAAACUAAAAAAAAAAAAAwAAAAABAAAAAAAAAMAAQAAAQQAAABMAAAAAAAAAAAAAAAAAAAAAAQRCAAgAAA8A8AIwAAAAAAgAQAgAWgAQAAAAIIAAAAAACAAAAAAAAAAQAAAAAAAAAAAAEAAAAAAAAQAICgAAAAAAIAAAAAAEAAAAAAAAAAAAAAAAAAAACAASAAAAAAAAAAAAAAAIADABAIAAAAADiAMAIAgAAAAAAAGgAeCAwRFAAAAAAAAAAAAAAAAAAAAAAAAA5ggDMIIAAEAAAAAAAAAAAAAAAAAAAAAAAAAABICLoEAAAAAAAMAg/d=0/dg=0/br=1/rs=ACT90oEpaZbQIBxtYflToMigkLE5nPLXWw/m=SMquOb,syyl,syyh,syev,d5EhJe,sy10x,sy1na,sy1n9,sy1n6,syyv,sy1n8,sy1n7,sy1n5,syvn,sy11o,sy11n,syyw,syvw,T1HOxc,LFk59d,sy16o,fCxEDd,syz1,syyt,syyq,syyr,syyo,syop,zx30Y,sy1nc,sy1nb,sy19u,syz4,Wo3n8,sy17t,EbPKJf,sy12r,sy12p,sylc,sypm,CnSW2d,sy17w,sy17v,pFsdhd,sy1qv,aBr2Mc,sy1qz,sy1qy,sy1qw,sy1a2,syvy,syrt,syrf,sypu,sysl,syw2,sy1qx,EkevXb,bIMMof,sy12x,sy12w,KbYvUc,sy1pl,sy12l,sy10r,sy10p,sygz,sy10w,sy10q,sy10z,sy1pk,KHourd,sy18n,sy18m,sy13i,oQfbDd,sy18x,sy18s,sy14b,syvc,syvg,syv1,syuz,syv0,syuy,syv2,sy18v,sy18w,sy18q,sy14a,sy18r,qmjr3,sy18p,IQw9J,sy19m,oSkgIf?xjs=s4"},{"scriptParseCompile":0,"scripting":9.596399999999997,"total":84.82080000000008,"url":"Unattributable"},{"scriptParseCompile":32.7228,"scripting":47.29560000000002,"total":83.67960000000002,"url":"https://www.gstatic.com/og/_/js/k=og.qtm.en_US._dvPeXVR4X8.2019.O/rt=j/m=qabr,q_d,qcwid,qapid,qads/exm=qaaw,qadd,qaid,qein,qhaw,qhba,qhbr,qhch,qhga,qhid,qhin/d=1/ed=1/rs=AA2YrTvQIrBtmHXP3htpEvFzVPlOIRB02Q"}],"sortedBy":["total"],"summary":{"wastedMs":704.9136000000012},"type":"table"},"displayValue":"0.7\u00a0s","id":"bootup-time","metricSavings":{"TBT":350},"numericUnit":"millisecond","numericValue":704.9136000000012,"score":1,"scoreDisplayMode":"metricSavings","title":"JavaScript execution time"},"cache-insight":{"description":"A long cache lifetime can speed up repeat visits to your page. [Learn more about caching](https://developer.chrome.com/docs/performance/insights/cache).","details":{"debugData":{"type":"debugdata","wastedBytes":0},"headings":[{"key":"url","label":"Request","valueType":"url"},{"displayUnit":"duration","key":"cacheLifetimeMs","label":"Cache TTL","valueType":"ms"},{"displayUnit":"kb","granularity":1,"key":"totalBytes","label":"Transfer Size","valueType":"bytes"}],"items":[],"type":"table"},"id":"cache-insight","metricSavings":{"FCP":0,"LCP":0},"score":1,"scoreDisplayMode":"metricSavings","title":"Use efficient cache lifetimes"},"cls-culprits-insight":{"description":"Layout shifts occur when elements move absent any user interaction. [Investigate the causes of layout shifts](https://developer.chrome.com/docs/performance/insights/cls-culprit), such as elements being added, removed, or their fonts changing as the page loads.","details":{"items":[],"type":"list"},"id":"cls-culprits-insight","metricSavings":{"CLS":0},"score":1,"scoreDisplayMode":"numeric","title":"Layout shift culprits"},"cumulative-layout-shift":{"description":"Cumulative Layout Shift measures the movement of visible elements within the viewport. [Learn more about the Cumulative Layout Shift metric](https://web.dev/articles/cls).","details":{"items":[{"cumulativeLayoutShiftMainFrame":0,"newEngineResult":{"cumulativeLayoutShift":0,"cumulativeLayoutShiftMainFrame":0},"newEngineResultDiffered":false}],"type":"debugdata"},"displayValue":"0","id":"cumulative-layout-shift","numericUnit":"unitless","numericValue":0,"score":1,"scoreDisplayMode":"numeric","title":"Cumulative Layout Shift"},"diagnostics":{"description":"Collection of useful page vitals.","details":{"items":[{"mainDocumentTransferSize":59540,"maxRtt":0.8999999999999999,"maxServerLatency":36,"numFonts":1,"numRequests":34,"numScripts":7,"numStylesheets":2,"numTasks":489,"numTasksOver100ms":1,"numTasksOver10ms":13,"numTasksOver25ms":8,"numTasksOver500ms":0,"numTasksOver50ms":5}]}}}}},"_note":"Response truncated for documentation purposes"}
curl --location --request GET 'https://zylalabs.com/api/10787/capture+website+performance+api/20440/perfomance+information?url=https://google.com' --header 'Authorization: Bearer YOUR_API_KEY'
| Header | Description |
|---|---|
Authorization
|
[Required] Should be Bearer access_key. See "Your API Access Key" above when you are subscribed. |
No long-term commitment. Upgrade, downgrade, or cancel anytime. Free Trial includes up to 50 requests.
The API returns a comprehensive performance audit for a given URL, including metrics like startup time, CPU usage, script execution time, caching efficiency, and layout stability indicators such as cumulative layout shift (CLS) and first contentful paint (FCP).
Key fields in the response include total block time (TBT), number of scripts and requests, JavaScript execution time, caching details, and layout shift metrics. Each field provides insights into specific performance aspects of the web page.
The response data is structured in a JSON format, with nested objects for different performance metrics. Each metric is clearly labeled, allowing users to easily identify and interpret the performance indicators relevant to their analysis.
The primary parameter for the endpoint is the URL of the web page to analyze. Users can customize their requests by including additional parameters, such as specific performance metrics they wish to focus on, if supported.
Typical use cases include optimizing website performance for better user experience, improving SEO rankings, identifying bottlenecks in loading times, and assessing the impact of JavaScript on page performance. Developers can use this data to prioritize optimizations.
Data accuracy is maintained through real-time analysis using advanced metrics and algorithms. The API continuously evaluates performance factors, ensuring that the information provided reflects the current state of the web page being analyzed.
Users can expect patterns such as high total block time indicating rendering delays, significant cumulative layout shifts suggesting visual instability, and long JavaScript execution times pointing to potential optimization areas. These patterns help prioritize improvements.
Users can utilize the returned data by analyzing key metrics to identify performance bottlenecks, implementing recommended optimizations, and monitoring changes over time. This data-driven approach enables informed decisions to enhance website performance.
Please have a look at our Refund Policy: https://zylalabs.com/terms#refund
To obtain your API key, you first need to sign in to your account and subscribe to the API you want to use. Once subscribed, go to your Profile, open the Subscription section, and select the specific API. Your API key will be available there and can be used to authenticate your requests.
You can’t switch APIs during the free trial. If you subscribe to a different API, your trial will end and the new subscription will start as a paid plan.
If you don’t cancel before the 7th day, your free trial will end automatically and your subscription will switch to a paid plan under the same plan you originally subscribed to, meaning you will be charged and gain access to the API calls included in that plan.
The free trial ends when you reach 50 API requests or after 7 days, whichever comes first.
No, the free trial is available only once, so we recommend using it on the API that interests you the most. Most of our APIs offer a free trial, but some may not include this option.
Yes, we offer a 7-day free trial that allows you to make up to 50 API calls at no cost, so you can test our APIs without any commitment.
Zyla API Hub is like a big store for APIs, where you can find thousands of them all in one place. We also offer dedicated support and real-time monitoring of all APIs. Once you sign up, you can pick and choose which APIs you want to use. Just remember, each API needs its own subscription. But if you subscribe to multiple ones, you'll use the same key for all of them, making things easier for you.
Service Level:
100%
Response Time:
1,151ms
Service Level:
100%
Response Time:
5,878ms
Service Level:
100%
Response Time:
18,624ms
Service Level:
100%
Response Time:
20,003ms
Service Level:
100%
Response Time:
20,003ms
Service Level:
100%
Response Time:
20,003ms
Service Level:
100%
Response Time:
297ms
Service Level:
100%
Response Time:
527ms
Service Level:
100%
Response Time:
875ms
Service Level:
100%
Response Time:
12,041ms
Service Level:
100%
Response Time:
5,247ms
Service Level:
100%
Response Time:
0ms
Service Level:
100%
Response Time:
5,664ms
Service Level:
100%
Response Time:
5,255ms
Service Level:
100%
Response Time:
198ms
Service Level:
100%
Response Time:
508ms
Service Level:
100%
Response Time:
3,903ms
Service Level:
100%
Response Time:
3,052ms
Service Level:
100%
Response Time:
1,064ms
Service Level:
100%
Response Time:
509ms
