How the numbers read
Ruby was 0.58–0.60% of justjoin.it offers in 2025, about 650–670 offers or 55 a month nationwide. justjoin.it publishes no junior Ruby figure because “niewielka liczba ofert dla juniorów sugeruje, że Ruby to język dla doświadczonych programistów” (the small number of junior offers suggests Ruby is a language for experienced developers).
Advertised ranges overstate mid-level pay: the survey puts real mid pay at 15,000 B2B and 12,500 UoP, against 19,000 and 15,500 offered. Product roles with a 2-year floor (Lipscore, Housecall Pro) and international employers with Polish bands (GitLab, Zendesk) reach 17,000–31,000. Kraków pays the highest rates of the nine large cities (mid-level B2B median upper bound 26,880), but there is no Kraków-specific junior data.
B2B vs UoP. justjoin.it puts the B2B premium at 15–26%: ~12.5% for juniors, ~26% for mids. Rule of thumb: UoP 12,000 gross ≈ B2B 14,000–15,000 net (justjoin.it blog). Junior ads still default to UoP (58%); mid ads are mostly B2B (72%). nofluffjobs flags EU-driven 2026 rules that would make reclassifying B2B as employment easier.
The AI premium. No source measures a premium for using AI tools as a generalist Rails developer. The AI/ML category does carry one: junior AI B2B 12,200–18,000 vs backend junior 7,000–10,000; mid AI 20,000–25,000 vs 17,000–22,000. That premium is earned by shipping LLM features.