Vela supports two order types: Limit and Market. Both types can be combined with any Time in Force setting to control execution behavior.
Limit Orders
Market Orders
A limit order specifies both the quantity and the maximum price you are willing to pay (buy) or the minimum price you are willing to accept (sell).Key properties:
- Will only execute at your specified price or better
- Rests in the order book if it cannot fill immediately (with GTC)
- Provides price certainty — you know the worst-case execution price
- May not fill immediately, or at all, if the market doesn’t reach your price
When to use limit orders:
- When the exact execution price matters to you
- When you want to enter or exit a position at a specific level
- When you are a market maker providing liquidity (combine with Post-Only TIF)
- When market impact is a concern and you want to avoid paying the spread
Example — Limit Buy:
You want to buy 1 ETH but only at 3,200 USDC or lower. You place a limit buy at 3200 for 1 ETH. If the best ask is currently 3250, your order rests in the book. When a seller is willing to sell at 3200 or below, your order fills.Example — Limit Sell:
You hold 2 ETH and want to sell if the price rises to 3,500 USDC. You place a limit sell at 3500 for 2 ETH. The order rests until a buyer arrives at that price or better. A market order executes immediately at the best available prices in the order book. You specify only the quantity — the price is determined by whatever liquidity is available.Key properties:
- Executes immediately (or is cancelled if no liquidity)
- No price guarantee — you receive the best available price, which may include slippage
- Useful when speed of execution matters more than price
- Can result in multiple fills at different prices if walking the book
When to use market orders:
- When you need to enter or exit immediately regardless of price
- When the spread is tight and slippage is minimal
- When the order size is small relative to available depth
Slippage warning:
A market order walks the book from the best price outward until the quantity is filled. On a thin book, this can result in fills at significantly worse prices than the best bid/ask. Always check the depth chart before placing a large market order.Example — Market Buy:
You place a market buy for 5 ETH. The order book has:
- 2 ETH available at 3200 USDC
- 2 ETH available at 3205 USDC
- 3 ETH available at 3210 USDC
Your order fills: 2 ETH at 3200, 2 ETH at 3205, 1 ETH at 3210. Average fill price: 3204 USDC.Market orders on thin markets can have significant slippage. Check the depth chart before placing large market orders.
Comparison
| Feature | Limit | Market |
|---|
| Price control | Yes — specify max/min price | No — takes best available |
| Guaranteed execution | No — may not fill | Yes — fills or cancels |
| Rests in book | Yes (with GTC) | No — immediate only |
| Slippage risk | None (or bounded) | Present on thin markets |
| Compatible TIF | GTC, IOC, FOK, Post-Only | IOC only (implicit) |
| Maker eligible | Yes | No — always taker |
Order Type and Fees
Market makers (limit orders that rest in the book) receive a different fee treatment than market takers (market orders and aggressive limit orders that immediately match). See Fees and Rebates for the full fee schedule.
Using Post-Only Time in Force with a limit order guarantees you will always be a maker. The order is rejected if it would match immediately, protecting you from accidentally paying taker fees.
Fixed-Point Price and Quantity
Prices and quantities submitted via the API are integers in fixed-point format scaled by 1,000,000:
| Human-readable | API value |
|---|
| 3200.00 USDC | 3200000000 |
| 0.5 ETH | 500000 |
| 0.001 BTC | 1000 |
