Paste your Gemfile.lock,
pick a target Rails version, and get the least compatible version of every gem —
checked against RubyGems and confirmed with a real Bundler resolution.
Just one gem? Look it up in the Gem Explorer →
- Least compatible version per gem
- Your Ruby version respected
- Rails runtime checks (sqlite3, pg, redis…)
- No account, no install
New analysis
Check your upgrade
- Latest Rails
- 8.1.4
- Targets available
- 10 series
- Data source
- RubyGems
What we check
More than “does it say railties < 8”
Every gem in your lockfile is checked against the exact Rails release you pick and the Ruby your project runs.
Least compatible version
For each gem, the lowest release at or above yours that fits — so you change as little as possible.
Your Ruby, not ours
Every candidate’s required Ruby is checked against the RUBY VERSION in your lockfile — and Bundler resolves as that Ruby.
Both directions
Not just what gems need from Rails — also what Rails needs from them, like i18n ≥ 1.6 or rack ≥ 2.2.4.
Runtime checks
Rails loads sqlite3, pg, mysql2, redis and others with version checks no gemspec mentions. We read them from Rails itself.
Confirmed with Bundler
All recommendations are pinned together and resolved in one real bundle lock against the target Rails.
Dead weight spotted
Gems only your old Rails pulled in — arel, erubis, thread_safe — are flagged as no longer needed.
How it works
From lockfile to upgrade plan in three steps
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1
Share your lockfile
Upload or paste Gemfile.lock. We read your gems, Rails version and Ruby version.
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2
Pick a target
Choose any newer Rails series published on RubyGems.
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3
Get your plan
See which gems are fine, which need a bump (and to what), and whether it all resolves together.
Ready to see your upgrade path?
It takes less than a minute. No signup.