Hyphen underscore or camelCase as word delimiter in URIs

Question

I m designing an HTTP-based API for an intranet app  I realize it s a pretty small concern in the grand scheme of things  but  should I use hyphens  underscores  or camelCase to delimit words in the URIs   Here are my initial thoughts  camelCase  possible issues if server is case-insensitive seems to have fairly widespread use in query string keys  http   api example com   searchQuery         but not in other URI parts  Hyphen  more aesthetically pleasing than the other alternatives seems to be widely used in the path portion of the URI never seen hyphenated query string key in the wild possibly better for SEO  this may be a myth   Underscore  potentially easier for programming languages to handle several popular APIs  Facebook  Netflix  StackExchange  etc   are using underscores in all parts of the URI   I m leaning towards underscores for everything  The fact that most of the big players are using them is compelling  see https   stackoverflow com a 608458 360570

User · Accepted Answer

You should use hyphens in a crawlable web application URL. Why? Because the hyphen separates words (so that a search engine can index the individual words), and is not a word character. Underscore is a word character, meaning it should be considered part of a word.

Double-click this in Chrome: camelCase
Double-click this in Chrome: under_score
Double-click this in Chrome: hyphen-ated

See how Chrome (I hear Google makes a search engine too) only thinks one of those is two words?

camelCase and underscore also require the user to use the shift key, whereas hyphenated does not.

So if you should use hyphens in a crawlable web application, why would you bother doing something different in an intranet application? One less thing to remember.

User · Answer

Whilst I recommend hyphens  I shall also postulate an answer that isn t on your list   Nothing At All   My company s API has URIs like  quotationrequests    purchaseorders  and so on  Despite you saying it was an intranet app  you listed SEO as a benefit  Google does match the pattern  foobar  in a URL for a query of  q foo bar I really hope you do not consider executing a PHP call to any arbitrary string the user passes in to the address bar  as  ServAce85 suggests

User · Answer

The standard best practice for REST APIs is to have a hyphen  not camelcase or underscores   This comes from Mark Masse s  REST API Design Rulebook  from Oreilly   In addition  note that Stack Overflow itself uses hyphens in the URL      hyphen-underscore-or-camelcase-as-word-delimiter-in-uris  As does WordPress  http   inventwithpython com blog 2012 03 18 how-much-math-do-i-need-to-know-to-program-not-that-much-actually

User · Answer

Short Answer   lower-cased words with a hyphen as separator  Long Answer   What is the purpose of a URL    If pointing to an address is the answer  then a shortened URL is also doing a good job   If we don t make it easy to read and maintain  it won t help developers and maintainers alike  They represent an entity on the server  so they must be named logically    Google recommends using hyphens     Consider using punctuation in your URLs  The URL http   www example com green-dress html is much more useful to us than http   www example com greendress html  We recommend that you use hyphens  -  instead of underscores     in your URLs    Coming from a programming background  camelCase is a popular choice for naming joint words    But RFC 3986 defines URLs as case-sensitive for different parts of the URL  Since URLs are case sensitive  keeping it low-key  lower cased  is always safe and considered a good standard  Now that takes a camel case out of the window    Source  https   metamug com article rest-api-naming-best-practices html word-delimiters

User · Answer

In general  it s not going to have enough of an impact to worry about  particularly since it s an intranet app and not a general-use Internet app  In particular  since it s intranet  SEO isn t a concern  since your intranet shouldn t be accessible to search engines   and if it is  it isn t an intranet app    And any framework worth it s salt either already has a default way to do this  or is fairly easy to change how it deals with multi-word URL components  so I wouldn t worry about it too much   That said  here s how I see the various options   Hyphen     The biggest danger for hyphens is that the same character  typically  is also used for subtraction and numerical negation  ie  minus or negative   Hyphens feel awkward in URL components  They seem to only make sense at the end of a URL to separate words in the title of an article  Or  for example  the title of a Stack Overflow question that is added to the end of a URL for SEO and user-clarity purposes    Underscore     Again  they feel wrong in URL components  They break up the flow  and beauty simplicity  of a URL  since they essentially add a big  heavy apparent space in the middle of a clean  flowing URL  They tend to blend in with underlines  If you expect your users to copy-paste your URLs into MS Word or other similar text-editing programs  or anywhere else that might pick up on a URL and style it with an underline  like links traditionally are   then you might want to avoid underscores as word separators  Particularly when printed  an underlined URL with underscores tends to look like it has spaces in it instead of underscores    CamelCase     By far my favorite  since it makes the URLs seem to flow better and doesn t have any of the faults that the previous two options do  Can be slightly harder to read for people that have a hard time differentiating upper-case from lower-case  but this shouldn t be much of an issue in a URL  because most  words  should be URL components and separated by a   anyways  If you find that you have a URL component that is more than 2  words  long  you should probably try to find a better name for that concept  It does have a possible issue with case sensitivity  but most platforms can be adjusted to be either case-sensitive or case-insensitive  Any it s only really an issue for 2 cases  a   humans typing the URL in  and b   Programmers  since we are not human  typing the URL in  Typos are always a problem  regardless of case sensitivity  so this is no different that all one case

User · Answer

here s the best of both worlds    I also  like  underscores  besides all your positive points about them  there is also a certain old-school style to them   So what I do is use underscores and simply add a small rewrite rule to your Apache s  htaccess file to re-write all underscores to hyphens   https   yoast com apache-rewrite-dash-underscore

User · Answer

It is recommended to use the spinal-case  which is highlighted by RFC3986   this case is used by Google  PayPal  and other big companies  source - https   blog restcase com 5-basic-rest-api-design-guidelines

[rest] Hyphen, underscore, or camelCase as word delimiter in URIs?

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