An example ENSEMBL gene ID identifier list:

ENSMUSG00000082108
ENSMUSG00000022485
ENSMUSG00000050621
ENSMUSG00000020387
ENSMUSG00000028626
ENSMUSG00000025400
ENSMUSG00000021268
ENSMUSG00000087095
ENSMUSG00000026247
ENSMUSG00000017344
ENSMUSG00000020427				

Will output:

ENSMUSG00000082108	Gm13777
ENSMUSG00000022485	Hoxc5
ENSMUSG00000050621	Rps27rt
ENSMUSG00000020387	Jade2
ENSMUSG00000028626	Col9a2
ENSMUSG00000025400	Tac2
ENSMUSG00000021268	Meg3
ENSMUSG00000087095	Emx2os
ENSMUSG00000026247	Ecel1
ENSMUSG00000017344	Vtn
ENSMUSG00000020427	Igfbp3

			

GET request for a single ID:

http://biotools.fr/mouse/ensembl_symbol_converter/?api=1&id=ENSMUSG00000082108
will output:

{"ENSMUSG00000082108":"Gm13777"}

POST request with ids submitted as a JSON array:

endpoint:	https://biotools.fr/mouse/ensembl_symbol_converter/
POST variables:
	api = 1
	ids = ["ENSMUSG00000082108","ENSMUSG00000022485","ENSMUSG00000050621"]

Will output:

{"ENSMUSG00000082108":"Gm13777","ENSMUSG00000022485":"Hoxc5","ENSMUSG00000050621":"Rps27rt"}

Example R code:

require(httr)
require(jsonlite)

###
# A single ID to convert - use a GET request
###
url = "http://biotools.fr/mouse/ensembl_symbol_converter/?api=1&id=ENSMUSG00000082108"
r <- GET(url)

output = fromJSON( content(r, "text"), flatten=TRUE)
df <- as.data.frame(output)
df


###
# Multiple IDs to convert - use a POST request
###
url = "http://biotools.fr/mouse/ensembl_symbol_converter/"
ids = c("ENSMUSG00000082108","ENSMUSG00000022485","ENSMUSG00000050621")
ids_json <- toJSON(ids)

body <- list(api=1, ids=ids_json)
r <- POST(url, body = body)

output = fromJSON( content(r, "text"), flatten=TRUE)
df <- as.data.frame(output)
df