> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/harness-platform/3.0/harness-platform-resources/variables-and-expressions.md).

# Variables & Expressions

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[Fixed values, runtime inputs, and expressions](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/runtime-inputs.md)
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[Use runtime input](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/runtime-input-usage.md)
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[Define variables](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/add-a-variable.md)
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[Use Harness expressions](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/harness-variables.md)
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[Built-in Variables List](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/harness-expressions-reference.md)
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[Branch-scoped build numbers](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/branch-build-sequence-id.md)
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[Use Java string methods](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/expressions-java-methods.md)
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[Use JSON parser tools and JEXL](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/expression-v2.md)
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[Output variables with chained pipeline](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/chained-pipeline-output-variables.md)
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[Variables and Expressions FAQ's](/harness-platform/3.0/harness-platform-resources/variables-and-expressions/variables-and-expressions-faqs.md)
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