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js-yaml

npm

YAML 1.2 parser and serializer

parserpyyamlserializeryaml
Versions collected93
Direct dependencies18From release 5.5.0
Last observed20 Oct, 15:25 UTC

README

Current package documentation

js-yaml

CI NPM version

YAML 1.2 parser and serializer for JavaScript.

Online demo

  • Supports the YAML 1.2 and YAML 1.1 specifications.
  • Passes the entire YAML Test Suite.

Documentation >>

Install
npm install js-yaml
Usage
import { load } from 'js-yaml'

try {
  const document = load('greeting: hello')
  console.log(document.greeting)
} catch (e) {
  console.error(e)
}

import { dump } from 'js-yaml'

const source = dump({ greeting: 'hello' })
console.log(source)

More usage examples.

Downloads & popularity

0downloads
1-day window · source-reported counts19 Oct 2026
64.8M32.4M0
2026-07-22: 48,882,149 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-22–2026-07-222026-07-23: 47,469,511 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-23–2026-07-232026-07-24: 42,835,666 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-24–2026-07-242026-07-25: 21,172,767 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-25–2026-07-252026-07-26: 21,441,413 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-26–2026-07-262026-07-27: 47,483,205 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-27–2026-07-272026-07-28: 49,857,168 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-28–2026-07-282026-07-29: 48,978,207 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-29–2026-07-292026-07-30: 49,095,606 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-30–2026-07-302026-07-31: 43,693,790 · observed 2026-10-20T08:44:03.2040594Z · period 2026-07-31–2026-07-312026-08-01: 23,774,414 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-01–2026-08-012026-08-02: 23,085,830 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-02–2026-08-022026-08-03: 49,159,468 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-03–2026-08-032026-08-04: 52,541,308 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-04–2026-08-042026-08-05: 51,774,822 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-05–2026-08-052026-08-06: 44,038,490 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-06–2026-08-062026-08-07: 47,383,864 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-07–2026-08-072026-08-08: 23,730,070 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-08–2026-08-082026-08-09: 23,637,372 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-09–2026-08-092026-08-10: 49,696,360 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-10–2026-08-102026-08-11: 51,532,312 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-11–2026-08-112026-08-12: 50,934,524 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-12–2026-08-122026-08-13: 50,544,041 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-13–2026-08-132026-08-14: 0 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-14–2026-08-142026-08-15: 23,348,188 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-15–2026-08-152026-08-16: 23,391,679 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-16–2026-08-162026-08-17: 45,787,034 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-17–2026-08-172026-08-18: 52,205,830 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-18–2026-08-182026-08-19: 50,795,697 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-19–2026-08-192026-08-20: 50,651,352 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-20–2026-08-202026-08-21: 45,619,743 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-21–2026-08-212026-08-22: 23,001,029 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-22–2026-08-222026-08-23: 23,651,406 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-23–2026-08-232026-08-24: 49,694,267 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-24–2026-08-242026-08-25: 52,475,661 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-25–2026-08-252026-08-26: 51,439,669 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-26–2026-08-262026-08-27: 52,369,622 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-27–2026-08-272026-08-28: 45,321,733 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-28–2026-08-282026-08-29: 23,276,988 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-29–2026-08-292026-08-30: 23,627,932 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-30–2026-08-302026-08-31: 49,343,709 · observed 2026-10-20T08:44:03.2040594Z · period 2026-08-31–2026-08-312026-09-01: 55,541,014 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-01–2026-09-012026-09-02: 57,482,427 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-02–2026-09-022026-09-03: 0 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-03–2026-09-032026-09-04: 49,257,042 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-04–2026-09-042026-09-05: 26,189,349 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-05–2026-09-052026-09-06: 25,917,323 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-06–2026-09-062026-09-07: 0 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-07–2026-09-072026-09-08: 0 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-08–2026-09-082026-09-09: 57,720,626 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-09–2026-09-092026-09-10: 56,163,631 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-10–2026-09-102026-09-11: 49,921,077 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-11–2026-09-112026-09-12: 25,220,836 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-12–2026-09-122026-09-13: 26,479,670 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-13–2026-09-132026-09-14: 55,929,507 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-14–2026-09-142026-09-15: 0 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-15–2026-09-152026-09-16: 56,107,613 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-16–2026-09-162026-09-17: 54,921,612 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-17–2026-09-172026-09-18: 50,788,335 · observed 2026-10-20T08:44:03.2040594Z · period 2026-09-18–2026-09-182026-09-19: 30,185,600 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-19–2026-09-192026-09-20: 30,300,770 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-20–2026-09-202026-09-21: 54,652,576 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-21–2026-09-212026-09-22: 57,188,515 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-22–2026-09-222026-09-23: 59,249,006 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-23–2026-09-232026-09-24: 59,200,500 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-24–2026-09-242026-09-25: 53,528,768 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-25–2026-09-252026-09-26: 28,038,268 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-26–2026-09-262026-09-27: 28,424,913 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-27–2026-09-272026-09-28: 61,432,202 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-28–2026-09-282026-09-29: 63,137,840 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-29–2026-09-292026-09-30: 63,761,519 · observed 2026-10-20T14:15:07.7602575Z · period 2026-09-30–2026-09-302026-10-01: 64,750,949 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-01–2026-10-012026-10-02: 55,492,333 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-02–2026-10-022026-10-03: 30,311,877 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-03–2026-10-032026-10-04: 30,064,467 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-04–2026-10-042026-10-05: 59,360,062 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-05–2026-10-052026-10-06: 0 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-06–2026-10-062026-10-07: 62,080,375 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-07–2026-10-072026-10-08: 63,437,594 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-08–2026-10-082026-10-09: 57,288,386 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-09–2026-10-092026-10-10: 30,195,134 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-10–2026-10-102026-10-11: 30,377,166 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-11–2026-10-112026-10-12: 56,693,902 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-12–2026-10-122026-10-13: 0 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-13–2026-10-132026-10-14: 0 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-14–2026-10-142026-10-15: 0 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-15–2026-10-152026-10-16: 58,670,189 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-16–2026-10-162026-10-17: 29,796,808 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-17–2026-10-172026-10-18: 30,992,862 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-18–2026-10-182026-10-19: 0 · observed 2026-10-20T14:15:07.7602575Z · period 2026-10-19–2026-10-19
22 Jul19 Oct

npm · 90 observations shown. Missing days are unknown.

View observed values
Date / source periodValueObserved at
2026-10-19 – 2026-10-1902026-10-20T14:15:07.7602575Z
2026-10-18 – 2026-10-1830,992,8622026-10-20T14:15:07.7602575Z
2026-10-17 – 2026-10-1729,796,8082026-10-20T14:15:07.7602575Z
2026-10-16 – 2026-10-1658,670,1892026-10-20T14:15:07.7602575Z
2026-10-15 – 2026-10-1502026-10-20T14:15:07.7602575Z
2026-10-14 – 2026-10-1402026-10-20T14:15:07.7602575Z
2026-10-13 – 2026-10-1302026-10-20T14:15:07.7602575Z
2026-10-12 – 2026-10-1256,693,9022026-10-20T14:15:07.7602575Z
2026-10-11 – 2026-10-1130,377,1662026-10-20T14:15:07.7602575Z
2026-10-10 – 2026-10-1030,195,1342026-10-20T14:15:07.7602575Z
2026-10-09 – 2026-10-0957,288,3862026-10-20T14:15:07.7602575Z
2026-10-08 – 2026-10-0863,437,5942026-10-20T14:15:07.7602575Z
2026-10-07 – 2026-10-0762,080,3752026-10-20T14:15:07.7602575Z
2026-10-06 – 2026-10-0602026-10-20T14:15:07.7602575Z
2026-10-05 – 2026-10-0559,360,0622026-10-20T14:15:07.7602575Z
2026-10-04 – 2026-10-0430,064,4672026-10-20T14:15:07.7602575Z
2026-10-03 – 2026-10-0330,311,8772026-10-20T14:15:07.7602575Z
2026-10-02 – 2026-10-0255,492,3332026-10-20T14:15:07.7602575Z
2026-10-01 – 2026-10-0164,750,9492026-10-20T14:15:07.7602575Z
2026-09-30 – 2026-09-3063,761,5192026-10-20T14:15:07.7602575Z
2026-09-29 – 2026-09-2963,137,8402026-10-20T14:15:07.7602575Z
2026-09-28 – 2026-09-2861,432,2022026-10-20T14:15:07.7602575Z
2026-09-27 – 2026-09-2728,424,9132026-10-20T14:15:07.7602575Z
2026-09-26 – 2026-09-2628,038,2682026-10-20T14:15:07.7602575Z
2026-09-25 – 2026-09-2553,528,7682026-10-20T14:15:07.7602575Z
2026-09-24 – 2026-09-2459,200,5002026-10-20T14:15:07.7602575Z
2026-09-23 – 2026-09-2359,249,0062026-10-20T14:15:07.7602575Z
2026-09-22 – 2026-09-2257,188,5152026-10-20T14:15:07.7602575Z
2026-09-21 – 2026-09-2154,652,5762026-10-20T14:15:07.7602575Z
2026-09-20 – 2026-09-2030,300,7702026-10-20T14:15:07.7602575Z
2026-09-19 – 2026-09-1930,185,6002026-10-20T14:15:07.7602575Z
2026-09-18 – 2026-09-1850,788,3352026-10-20T08:44:03.2040594Z
2026-09-17 – 2026-09-1754,921,6122026-10-20T08:44:03.2040594Z
2026-09-16 – 2026-09-1656,107,6132026-10-20T08:44:03.2040594Z
2026-09-15 – 2026-09-1502026-10-20T08:44:03.2040594Z
2026-09-14 – 2026-09-1455,929,5072026-10-20T08:44:03.2040594Z
2026-09-13 – 2026-09-1326,479,6702026-10-20T08:44:03.2040594Z
2026-09-12 – 2026-09-1225,220,8362026-10-20T08:44:03.2040594Z
2026-09-11 – 2026-09-1149,921,0772026-10-20T08:44:03.2040594Z
2026-09-10 – 2026-09-1056,163,6312026-10-20T08:44:03.2040594Z
2026-09-09 – 2026-09-0957,720,6262026-10-20T08:44:03.2040594Z
2026-09-08 – 2026-09-0802026-10-20T08:44:03.2040594Z
2026-09-07 – 2026-09-0702026-10-20T08:44:03.2040594Z
2026-09-06 – 2026-09-0625,917,3232026-10-20T08:44:03.2040594Z
2026-09-05 – 2026-09-0526,189,3492026-10-20T08:44:03.2040594Z
2026-09-04 – 2026-09-0449,257,0422026-10-20T08:44:03.2040594Z
2026-09-03 – 2026-09-0302026-10-20T08:44:03.2040594Z
2026-09-02 – 2026-09-0257,482,4272026-10-20T08:44:03.2040594Z
2026-09-01 – 2026-09-0155,541,0142026-10-20T08:44:03.2040594Z
2026-08-31 – 2026-08-3149,343,7092026-10-20T08:44:03.2040594Z
2026-08-30 – 2026-08-3023,627,9322026-10-20T08:44:03.2040594Z
2026-08-29 – 2026-08-2923,276,9882026-10-20T08:44:03.2040594Z
2026-08-28 – 2026-08-2845,321,7332026-10-20T08:44:03.2040594Z
2026-08-27 – 2026-08-2752,369,6222026-10-20T08:44:03.2040594Z
2026-08-26 – 2026-08-2651,439,6692026-10-20T08:44:03.2040594Z
2026-08-25 – 2026-08-2552,475,6612026-10-20T08:44:03.2040594Z
2026-08-24 – 2026-08-2449,694,2672026-10-20T08:44:03.2040594Z
2026-08-23 – 2026-08-2323,651,4062026-10-20T08:44:03.2040594Z
2026-08-22 – 2026-08-2223,001,0292026-10-20T08:44:03.2040594Z
2026-08-21 – 2026-08-2145,619,7432026-10-20T08:44:03.2040594Z
2026-08-20 – 2026-08-2050,651,3522026-10-20T08:44:03.2040594Z
2026-08-19 – 2026-08-1950,795,6972026-10-20T08:44:03.2040594Z
2026-08-18 – 2026-08-1852,205,8302026-10-20T08:44:03.2040594Z
2026-08-17 – 2026-08-1745,787,0342026-10-20T08:44:03.2040594Z
2026-08-16 – 2026-08-1623,391,6792026-10-20T08:44:03.2040594Z
2026-08-15 – 2026-08-1523,348,1882026-10-20T08:44:03.2040594Z
2026-08-14 – 2026-08-1402026-10-20T08:44:03.2040594Z
2026-08-13 – 2026-08-1350,544,0412026-10-20T08:44:03.2040594Z
2026-08-12 – 2026-08-1250,934,5242026-10-20T08:44:03.2040594Z
2026-08-11 – 2026-08-1151,532,3122026-10-20T08:44:03.2040594Z
2026-08-10 – 2026-08-1049,696,3602026-10-20T08:44:03.2040594Z
2026-08-09 – 2026-08-0923,637,3722026-10-20T08:44:03.2040594Z
2026-08-08 – 2026-08-0823,730,0702026-10-20T08:44:03.2040594Z
2026-08-07 – 2026-08-0747,383,8642026-10-20T08:44:03.2040594Z
2026-08-06 – 2026-08-0644,038,4902026-10-20T08:44:03.2040594Z
2026-08-05 – 2026-08-0551,774,8222026-10-20T08:44:03.2040594Z
2026-08-04 – 2026-08-0452,541,3082026-10-20T08:44:03.2040594Z
2026-08-03 – 2026-08-0349,159,4682026-10-20T08:44:03.2040594Z
2026-08-02 – 2026-08-0223,085,8302026-10-20T08:44:03.2040594Z
2026-08-01 – 2026-08-0123,774,4142026-10-20T08:44:03.2040594Z
2026-07-31 – 2026-07-3143,693,7902026-10-20T08:44:03.2040594Z
2026-07-30 – 2026-07-3049,095,6062026-10-20T08:44:03.2040594Z
2026-07-29 – 2026-07-2948,978,2072026-10-20T08:44:03.2040594Z
2026-07-28 – 2026-07-2849,857,1682026-10-20T08:44:03.2040594Z
2026-07-27 – 2026-07-2747,483,2052026-10-20T08:44:03.2040594Z
2026-07-26 – 2026-07-2621,441,4132026-10-20T08:44:03.2040594Z
2026-07-25 – 2026-07-2521,172,7672026-10-20T08:44:03.2040594Z
2026-07-24 – 2026-07-2442,835,6662026-10-20T08:44:03.2040594Z
2026-07-23 – 2026-07-2347,469,5112026-10-20T08:44:03.2040594Z
2026-07-22 – 2026-07-2248,882,1492026-10-20T08:44:03.2040594Z

Versions 93

Collected releases
VersionPublishedDirect dependenciesOpen version
3.6.111 May 201610
3.6.015 Apr 201610
3.5.517 Mar 201610
3.5.49 Mar 201610
3.5.311 Feb 201610
3.5.211 Jan 201611
3.5.111 Jan 201611
3.5.010 Jan 201611
3.4.626 Nov 20159
3.4.523 Nov 20158
3.4.421 Nov 20158
3.4.310 Oct 20158
3.4.29 Sept 20158
3.4.14 Sept 20158
3.4.022 Aug 20158
3.3.113 May 20158
3.3.026 Apr 20158
3.2.719 Feb 20155
3.2.67 Feb 20155
3.2.527 Dec 20145
Sorted by available source dates · UTC

Package advisories

9
GHSA-52cp-r559-cp3mOSV

js-yaml: YAML merge-key chains can force quadratic CPU consumption

Source record
GHSA-mh29-5h37-fv8mOSV

js-yaml has prototype pollution in merge (<<)

Source record
GHSA-724g-mxrg-4qvmOSV

js-yaml: Quadratic-complexity (O(n^2)) DoS via !!omap tag in YAML11_SCHEMA

Source record
GHSA-r3ph-w7gj-g6xmOSV

js-yaml: maxTotalMergeKeys does not limit CPU use for empty merge sources

Source record
GHSA-2883-xcg3-v3hhOSV

js-yaml: maxTotalMergeKeys does not limit CPU use for empty merge sources

Source record
GHSA-5p4m-2wfm-xmqjOSV

JS-YAML: Quadratic CPU consumption in !!omap resolution (3.x and 4.x) — CVE-2026-59870 fix not backported

Source record
GHSA-g796-fgmg-93mvOSV

js-yaml: YAML merge-key chains can force quadratic CPU consumption in js-yaml

Source record
GHSA-pm4m-ph32-ghv5OSV

js-yaml: Exponential parsing time in flow collections leads to denial of service

Source record
GHSA-h67p-54hq-rp68OSV

JS-YAML: Quadratic-complexity DoS in merge key handling via repeated aliases

Source record

Matched to the package identity. Affected version ranges have not been evaluated.

Repository

PENDING
nodeca/js-yaml

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Metadata history

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Current collected state Current

Observed since 20 Oct, 08:14 UTC

No superseded metadata states collected. Unchanged observations do not create new revisions.

Record identity

package:86e0c03c5deaccd3a5c0076a0e9a8f86ae19f9956453ce9cca92f69a95aef6cc