Crypto Newbie / Simulators / Orderbook DEX
Orderbook DEX Simulator — Limit, Market, AMM Comparison
Hyperliquid, dYdX, Serum, Binance, and almost every CEX use a central limit orderbook (CLOB) instead of an AMM. The difference: an orderbook is a list of resting bids + asks that takers sweep through; an AMM is a mathematical bonding curve. CLOBs are usually more capital-efficient for liquid markets, AMMs are simpler and don't need market makers. This simulator runs a real matching engine — place orders, watch them rest, then sweep with a market order to see slippage.
Best bid
100.00
Best ask
100.25
Spread
0.25
Mid
100.13
Order book
Bids (buyers)
| Price | Size |
|---|---|
| 100.00 | 20.00 |
| 99.75 | 20.00 |
| 99.50 | 20.00 |
| 99.25 | 20.00 |
| 99.00 | 20.00 |
| 98.75 | 20.00 |
| 98.50 | 20.00 |
| 98.25 | 20.00 |
Asks (sellers)
| Price | Size |
|---|---|
| 100.25 | 20.00 |
| 100.50 | 20.00 |
| 100.75 | 20.00 |
| 101.00 | 20.00 |
| 101.25 | 20.00 |
| 101.50 | 20.00 |
| 101.75 | 20.00 |
| 102.00 | 20.00 |
Place limit order
Place market order
Recent trades
No trades yet.
How limit orders rest, market orders sweep
A limit buy at $100 says 'I'll pay no more than $100 per unit'. If the best ask is $102, the order rests on the book at $100 (it doesn't fill). When a seller arrives willing to sell at $100, they can match against your resting order. A market buy says 'fill any quantity available, I don't care about price' — it consumes the asks from cheapest to most expensive until the size is filled. The deeper the book at the touch, the less slippage market orders incur.
Spread + depth — the two numbers that matter
Spread = bestAsk − bestBid. Tighter spread = lower cost to trade. Depth = total size at or near the touch. Deeper book = larger market orders execute without moving the price. A 'thin book' has wide spread and small depth — common for low-volume altcoins; market orders incur 1-5% slippage even on small sizes. A 'deep book' has tight spread + large depth — common for BTC/USD on major venues; you can sweep $1M without moving 5 ticks. Try the two presets in the simulator to feel the difference.
Why orderbook DEXes feel faster but need market makers
An AMM always has a price (because the formula always returns one). An orderbook only has a price when someone has placed a bid AND an ask. Without market makers actively quoting both sides, an orderbook is empty and unusable. Hyperliquid, dYdX etc. attract market makers with rebates, taker fees, and incentive programs. AMMs need no market makers — they're permissionlessly priced. The trade-off: AMMs have predictable slippage that scales with pool depth; orderbooks have discretionary slippage that depends on whoever's quoting that minute.
When AMM beats CLOB and vice versa
CLOB wins: high-volume, well-known pairs where MM competition is fierce (BTC/USD, ETH/USDC on Binance). Spreads collapse to 1-2 bps, market orders cost almost nothing. AMM wins: long-tail pairs where no MM bothers (random ERC20 / WETH), permissionless launches where no order entry interface exists, and use cases requiring trustless settlement (Uniswap, no off-chain order entry). The simulator's 'equivalent AMM price' lets you see for yourself when each model is cheaper.
Frequently asked questions
+Why don't all DEXes use orderbooks if they're more efficient?
Two reasons: (1) Orderbooks need active market makers to function — without them the book is empty. AMMs work even with zero participation. (2) On-chain orderbooks are gas-expensive — every order placement/cancellation is a transaction. Hyperliquid solves this by running an off-chain matching engine with on-chain settlement; on-chain CLOBs (Serum) struggled with Ethereum gas. AMMs were the breakthrough that made DEXes usable on Ethereum.
+What's a 'maker' vs 'taker' order?
Maker = limit order that rests on the book without matching (you're MAKING liquidity). Taker = order that matches against existing resting orders (you're TAKING liquidity). Most venues charge taker fees (you pay for liquidity provided by others) and pay maker rebates (you get paid to provide liquidity). Active traders structure orders to be makers when possible — over time, the fee difference compounds significantly.
+What is slippage exactly?
The difference between the price you EXPECTED (best touch price) and the price you ACTUALLY paid (volume-weighted average across the depth you consumed). On a 10% slippage trade, paying $100 average when best ask was $90.91, you 'lost' $9.09 per unit to slippage. This is on top of any explicit fees the venue charges.
+Can I place a limit order that fills immediately?
Yes — if your limit crosses the spread (limit buy ≥ best ask, or limit sell ≤ best bid), the matching engine fills it against resting orders. Any unfilled remainder rests on the book at your limit. This is called a 'marketable limit order' — gives you protection against slippage (won't fill above your limit) while still getting immediate execution if possible.
+Why does the simulator's AMM comparison sometimes show AMM cheaper?
Because at small sizes against deep books with tight spreads, the AMM's pricing curve is essentially flat in the trading range, while orderbook execution still pays the spread. At larger sizes (relative to book depth) the orderbook wins because depth runs out and slippage explodes on AMM curves. The crossover point depends on book depth vs AMM pool depth — try both preset books to see when each model wins.