Resource Hints: preconnect

Gives a hint to the browser to begin the connection handshake (DNS, TCP, TLS) in the background to improve performance. This is indicated using <link rel="preconnect" href="https://example-domain.com/">

Spec	https://www.w3.org/TR/resource-hints/#preconnect
Status	W3C Working Draft

IE	Edge	Firefox	Chrome	Safari	Opera
			108
		107	107	TP
		106	106	16.1
11	105	105	105	16.0	91
10	104	104	104	15.6	90
9	103	103	103	15.5	89
8	102	102	102	15.4	88
Show all
7	101	101	101	15.2-15.3	87
6	100	100	100	15.1	86
5.5	99	99	99	15	85
	98	98	98	14.1	84
	97	97	97	14	83
	96	96	96	13.1	82
	95	95	95	13	81
	94	94	94	12.1	80
	93	93	93	12	79
	92	92	92	11.1	78
	91	91	91	11	77
	90	90	90	10.1	76
	89	89	89	10	75
	88	88	88	9.1	74
	87	87	87	9	73
	86	86	86	8	72
	85	85	85	7.1	71
	84	84	84	7	70
	83	83	83	6.1	69
	81	82	81	6	68
	80	81	80	5.1	67
	79	80	79	5	66
	18 (2)	79	78	4	65
	17 (2)	78	77	3.2	64
	16 (2)	77	76	3.1	63
	15 (2)	76	75		62
	14	75	74		60
	13	74	73		58
	12	73	72		57
		72	71		56
		71	70		55
		70	69		54
		69	68		53
		68	67		52
		67	66		51
		66	65		50
		65	64		49
		64	63		48
		63	62		47
		62	61		46
		61	60		45
		60	59		44
		59	58		43
		58	57		42
		57	56		41
		56	55		40
		55	54		39
		54	53		38
		53	52		37
		52	51		36
		51	50		35
		50	49		34
		49	48		33
		48	47		32
		47	46		31
		46	45		30
		45	44		29
		44	43		28
		43	42		27
		42	41		26
		41	40		25
		40	39		24
		39 (1)	38		23
		38	37		22
		37	36		21
		36	35		20
		35	34		19
		34	33		18
		33	32		17
		32	31		16
		31	30		15
		30	29		12.1
		29	28		12
		28	27		11.6
		27	26		11.5
		26	25		11.1
		25	24		11
		24	23		10.6
		23	22		10.5
		22	21		10.0-10.1
		21	20		9.5-9.6
		20	19		9
		19	18
		18	17
		17	16
		16	15
		15	14
		14	13
		13	12
		12	11
		11	10
		10	9
		9	8
		8	7
		7	6
		6	5
		5	4
		4
		3.6
		3.5
		3
		2

Safari on iOS	Opera Mini	Android Browser	Blackberry Browser	Opera Mobile	Android Chrome	Android Firefox	IE Mobile	Android UC Browser	Samsung Internet	QQ Browser	Baidu Browser	KaiOS Browser
16.1
16.0	all	105	10	64	105	104	11	13.4	18.0	13.1	13.18	2.5
15.6		4.4.3-4.4.4	7	12.1			10		17.0
15.5		4.4		12					16.0
15.4		4.2-4.3		11.5					15.0
Show all
15.2-15.3		4.1		11.1					14.0
15.0-15.1		4		11					13.0
14.5-14.8		3		10					12.0
14.0-14.4		2.3							11.1-11.2
13.4-13.7		2.2							10.1
13.3		2.1							9.2
13.2									8.2
13.0-13.1									7.2-7.4
12.2-12.5									6.2-6.4
12.0-12.1									5.0-5.4
11.3-11.4									4
11.0-11.2
10.3
10.0-10.2
9.3
9.0-9.2
8.1-8.4
8
7.0-7.1
6.0-6.1
5.0-5.1
4.2-4.3
4.0-4.1
3.2

Notes

1. Firefox 39 did not support 'crossorigin' attribute and preconnects were not processed by the preload parser. Both of these features were enabled in Firefox 41.

2. Partial support in Edge 15+ refers to support for only the HTTP header format, not the <link rel> format.

3. Appears to have stopped working in Firefox at some point.

Resources

• Eliminating Roundtrips with Preconnect