Unpaywall open-access lookup by DOI (free API; it requires a contact e-mail set in UNPAYWALL_EMAIL, not a key): is the paper open access, OA status, best free full-text link, journal and publisher. Returns metadata and links only, not the PDF.
| Network | Scheme | Amount | Pay To |
|---|---|---|---|
| Base | exact | $0.002000 USDC | 0xb849...eAfA |
| solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp | exact | 0.00 tokens | J8vnmB...RdhR |
| eip155:5042 | exact | 0.00 tokens | 0xa475...9be3 |
| Polygon | exact | $0.002000 USDC | 0xb849...eAfA |
| Arbitrum One | exact | $0.002000 USDC | 0xb849...eAfA |
| eip155:143 | exact | 0.00 tokens | 0xb849...eAfA |
| eip155:480 | exact | 0.00 tokens | 0xb849...eAfA |
| Optimism | exact | $0.002000 USDC | 0xb849...eAfA |
| Celo | exact | 0.00 tokens | 0xb849...eAfA |
| stellar:pubnet | exact | 0.02 tokens | GBIX2M...OAFI |
| xrpl:0 | exact | 0.002 | rDxNZC...f8UJ |
| xrpl:0 | exact | 0.00 tokens | rDxNZC...f8UJ |