guardian/commercial-canaries
AWS Synthetic Canaries that monitor ads on the Guardian website
GitHub 
1K
lines of main code
12 files
4.6K
lines of test code
4 files
5.5K
lines of other code
14 files
6y
age
2,130 days
99%
main code touched
1 year (1K LOC)
ABCDE
ease of change
for people*
ABCDE
ease of change
for AI*
0.8K
js
0.2K
ts
0.06K
yaml
MJS
0.01K
mjs
30 days 2026 2025 2024 2023 2022 2021 2020
+363
-325
+1.3K
-893
+2.2K
-1.8K
+430
-176
+34
-40
+2.6K
-1.7K
+707
-106
+197
-63
40

119

131

48

23

132

30

16

14

39

60

29

13

69

22

6

2

4

8

5

4

5

4

1

2026 2025 2024 2023 2022 2021 2020
Rule-of-thumb estimates

Rebuild value

to rebuild
rebuild value

Maintenance effort

per year to maintain
maintenance cost per year
Rules of thumb, not measurements: one man-year rebuilds about 10,000 lines of main code (design, testing and coordination included), and keeping a code base alive takes about 15% of its rebuild value per year (20 man-years of rebuild value need about 3 man-years of maintenance every year). Your changes are remembered in this browser for every report.