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Income Tax - Major components of deferred tax assets and liabilities (Details) - USD ($) $ in Thousands | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | --- | ---
Deferred tax assets: |  |  |
Net operating loss carryforward | $ 58,975 | $ 52,948 |
Research and development credit carryforward | 4,522 | 1,723 |
Stock-based compensation | 4,128 | 3,879 |
Section 174 Research and Development Capitalization | 15,982 | 3,553 |
Lease liability | 1,143 | 737 |
Other | 1,260 | 2,053 |
Total deferred tax assets | 86,010 | 64,893 |
Deferred tax liabilities: |  |  |
Right-of-use assets | (1,085) | (651) |
Other | (174) | (226) |
Total deferred tax liabilities | (1,259) | (877) |
Net deferred tax assets before valuation allowance | 84,751 | 64,016 |
Valuation allowance | (84,751) | (64,016) | $ (51,746)
Deferred tax, net | $ 0 | $ 0 |

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