Comprehensive tutorials and resources for mainframe technologies and COBOL programming.
Who it is for
Beginners and career changers learning COBOL and enterprise mainframe skills.
The solution
MainframeMaster publishes free tutorials for COBOL, JCL, CICS, DB2, VSAM, IBM MQ, DFSORT, Easytrieve, and TSO/ISPF. Learn the skills that still run banking, insurance, and government systems.
Features3 listed
COBOL programming tutorials
JCL and CICS guides
DB2 and VSAM learning material
Details
Built for
Beginners and career changers learning COBOL and enterprise mainframe skills.
In IndieTools' mobile lab test on July 5, 2026, the MainframeMaster website scored 73 out of 100 (needs improvement). Largest Contentful Paint took 9.25 s, rated poor. It placed #67 overall in the finalized week 2026-W27.
Measured (UTC)
LCPLargest Contentful Paint
9.25 s
Poor
TBTTotal Blocking Time
109 ms
Good
CLSCumulative Layout Shift
0.000
Good
FCPFirst Contentful Paint
937 ms
Good
Ranked #67 overall in 2026-W27, best #24.
MainframeMaster lab metrics
Speed metrics for MainframeMaster, measured July 5, 2026
Metric
Result
Status
Trend
Mobile lab testMid-range phone on a throttled 4G connection, two runs averaged. Changes compare with the run on Jul 3.
Performance score
Needs improvementUp 4 points
73 / 100
Needs improvementUp 4 points
First Contentful PaintFCP
GoodAbout the same
937 ms
GoodAbout the same
Largest Contentful PaintLCP
Poor1.76 s faster
9.25 s
Poor1.76 s faster
Speed IndexSI
Needs improvement901 ms faster
3.58 s
Needs improvement901 ms faster
Total Blocking TimeTBT
Good96 ms faster
109 ms
Good96 ms faster
Cumulative Layout ShiftCLS
GoodAbout the same
0.000
GoodAbout the same
Unthrottled observationsTimed on the test machine's own fast connection, so they read lower than the lab metrics above.
Page loadLoad
1.76 s faster
9.25 s
1.76 s faster
Server responseTTFB
No trend yet
Not recorded
No trend yet
MainframeMaster performance history
105 comparable mobile lab runs since February 20, 2026. Choose a metric and a range, then move along the line to read each run.
MainframeMaster Speed ranking
Weekly Speed standing for MainframeMaster
Weekly standingLatest finalized week 2026-W27. Bests cover the last 52 finalized weeks.
Overall rank, 2026-W27
Down 1 place
#67
Down 1 place
Best overall rank
#24
Best finalized score
73 / 100
Stored lab observations from controlled test runs, not real-user Core Web Vitals or a guarantee of search rankings. Weekly standings remain attached to their finalized edition.Method legacy-unspecified, 1 samples per reading. Lab results can vary between runs.
Model difference−10. DR4 is 10 points lower than DR3.
Measured · mainframemaster.com
What do DR4, DR3 and the model difference mean?
DR4:
Ahrefs' newer model. It gives more weight to links from sites with organic search traffic and rates a subdomain on its own links.
DR3:
The previous model, shown in the Ahrefs app until 1 December 2026.
Model difference:
DR4 minus DR3 for the same domain. The models calculate differently, so this is not growth or a drop; the “since” lines compare each model with itself.