solana-system-interface is used at run time in 210 crates (of which 14 optionally). It is a direct run-time dependency in 34 crates. It's used only as a dev dependency in 22 crates (of which 6 directly).

Depender (with downloads and own rev deps) solana-system-interface version
493K 83 spl-token-2022 ^1.0.0
394K 646 solana-program ^1.0
173K 2 spl-elgamal-registry ^1.0.0
164K 15 solana-config-program ^1.0
139K 8 solana-stake-interface ^1.0
136K 3 solana-thin-client ^1.0
137K 142 solana-transaction-status ^1.0
133K 2 solana-example-mocks ^1.0
96K 5 solana-client-traits ^1.0
93K 12 solana-system-transaction ^1.0
63K 21 solana-address-lookup-table-program ^1.0
150K 5 solana-vote-interface optional ^1.0
146K 48 solana-message optional ^1.0
138K 24 solana-perf optional ^1.0
136K 4 solana-feature-gate-interface optional ^1.0
135K 9 solana-loader-v3-interface optional ^1.0
44K 22 solana-bpf-loader-program ^1.0
134K 6 solana-loader-v4-interface optional ^1.0
43K 10 solana-system-program ^1.0
37K 9 solana-faucet ^1.0
33K 5 solana-cost-model ^1.0
102K 44 solana-transaction optional ^1.0
17K 27 solana-cli-output ^1.0
6.4K 3 litesvm ^1
1.2K 3 solana-cli ^1.0
250 1 surfpool-core ^1.0.0
240 litesvm-token ^1
spherenet-program ^1.0
1 spherenet-stake-interface ^1.0
225K 14 solana-cpi dev ^1.0
223K 15 solana-bincode dev ^1.0
136K 3 solana-rpc-client-nonce-utils dev ^1.0
98K 31 solana-transaction-context dev ^1.0
92K 47 solana-clap-utils dev ^1.0
29K 12 solana-svm-transaction dev ^1.0
27K 3 agave-transaction-view dev ^1.0
26K 10 solana-runtime-transaction dev ^1.0
18K 6 solana-compute-budget-instruction dev ^1.0
15K 11 solana-clap-v3-utils dev ^1.0
1.1K 7 mollusk-svm dev ^1.0