demo · v142

Dictionary TTL

Pick a TTL, cache lifetime, and elapsed time. The simulator shows the Use-As-Dictionary response header the server would send, including the ttl=0 immediately-expires corner case, and tells you whether the browser would still offer the dictionary on the next request.

86400 (1d)

Set ttl to 0 to emit an explicit immediately-expiring dictionary: the response can register the dictionary, but no subsequent request should offer it.

When ttl is omitted, this demo falls back to the older default: dictionary usefulness follows the HTTP cache lifetime.

3600 (1h)
3600 (1h)
server response (dictionary fetch)

    


    

      
subsequent request (1 hour later)

      

    


    

      

        
dictionary state

        
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expires in

        
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HTTP cache state

        
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lifetime rule

        
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Client-side simulation. Real verification requires a server that issues the Use-As-Dictionary header and a browser with Compression Dictionary Transport enabled (Chrome 142+).

  


  
relevant API


Use-As-Dictionary: match="/page-*", ttl=86400

# After ttl seconds the browser evicts the dictionary,
# so subsequent requests fall back to baseline encoding.


  

    
see also